IDOMENI, Greece (AP) — Desperate migrants and refugees piled up Thursday in fetid fields of mud at a closed border crossing as officials warned that a well-trodden route to Europe used by hundreds of thousands in the past year was no longer available.

With the closure of the migrant trail through the Balkans from Greece to more prosperous countries, concern also mounted that people desperate for sanctuary or jobs in Europe are already turning to smugglers to find other pathways.

Government ministers and experts say that Albania, Hungary, Bulgaria and Romania could become alternate tracks, and officials Spain are in contact with Algeria and Morocco to try to stop new routes from opening there.

At the same time, the flow continued to the Greek islands by boat from Turkey, either by those who have not heard the Greece-Macedonia crossings are no longer open, or by others who hope the closure is temporary.

Some didn't make it. Turkey's state-run Anadolu news agency said five people, including a 3-month-old, drowned when their speedboat sank Thursday off Turkey's western coast en route to the Greek island of Lesbos. Nine people were rescued from the boat, which was carrying Afghans and Iranians, the agency said.

NATO stepped up its operations to try to stop the smugglers, deploying five ships in the Aegean Sea, with plans to send more in the coming days to monitor the area near the Greek island of Lesbos and areas farther south, said Jens Stoltenberg, the secretary-general of the alliance.

Meanwhile, Greek police said 81 economic migrants from Pakistan and north Africa who had entered the country illegally were deported back to Turkey.

Nearly 42,000 people are stranded in Greece, including 14,000 camped in the mud near the Idomeni crossing with Macedonia. Nearly three days of rain finally ended, but that did little to lift the misery for those staying in donated pup tents in nearby fields and along railway tracks.

Long lines formed for sandwiches, tea and soup at the Idomeni camp, which long ago surpassed its capacity. Others warmed themselves at fires using what dry wood they could find, or they poured oil on sodden logs to get them to burn.

The fields have grown increasingly fetid, with pools of water and deep mud that sucks the shoes off children. People dragged their muddy tents to new locations, looking for a dry patch of ground.

Many people who have spent days at the camp in chilly temperatures were coughing heavily.

A crowd formed at a truck of donated goods, with men tossing bags of diapers, toilet paper, bottled water, yogurt and prepared meals to the cheering crowd. Dozens of packaged meals ended up falling to the ground, with cooked pasta and yogurt splattering in the mud.

Some people gave up and boarded buses for refugee camps in and around Athens.

"May God take his revenge on them — everyone who did this to us — from whatever country they come from," said Raife al-Baltajy, a Syrian from near Aleppo, as she waited for a bus with her family. "May god take his vengeance out on them. Isn't it sinful? Are we animals? Or are we human beings?"

She said she had been living in Syria for four years under the shelling, but traveled to Turkey, then to the Greek island of Lesbos, where she took a ferry to the mainland and on to Idomeni.

"Under this rain, in the cold. Who wants to protect us?" she said.

Government health experts say there is no sign yet of infectious disease at the camp, but they have been urging people to move to nearby army-built shelters. Authorities say about 70 children at the camp have received treatment in the past three days for fever and diarrhea.

Almaz Moho, a Syrian Kurd who traveled from Aleppo with her three daughters, one of them an infant born in Istanbul, said they came to Idomeni "because they said the borders are open," but found out otherwise.

"And they're unsettling the children, between the filth, the dust, under the pouring rain, with little food and soaked clothes," she said. "Where do you want us to go? Where do they want us to go? We have no homes."

As European Union interior ministers met in Brussels on the crisis, Austria urged migrants to give up hope of moving on.

"The Balkan route is closed," Austrian Interior Minister Johanna Mikl-Leitner told reporters. "The biggest problem is that these refugees still have hopes and expectations, and these hopes are being constantly fed."

Germany was critical, despite the benefits of having to cope with a big drop in migrant flows due to the border closures that were prompted by Austria's decision to impose a cap on refugee numbers.

That "brings us fewer refugees, but on the other hand puts Greece in a very difficult situation. And this situation is not durable and sustainable," Mikl-Leitner said.

More than 1 million people have come to Europe in the past year, most of them by boat from Turkey to Greece, fleeing war, persecution or abysmal poverty. Once taken to the Greek mainland from their island arrival points, most headed to the Macedonian border, then onward to Serbia, Croatia and Slovenia, before moving on to Austria and other prosperous EU nations.

Passage through those nations began being restricted last month, and on Monday, countries along the Balkan route decided to allow entry only to people with valid EU visas. But even as those countries shut their borders, others braced for an influx of people taking alternate routes — and risking new dangers — in their search for a new life.

EU and Turkish leaders agreed Monday to the broad outlines of a deal that would see people arriving in Greece having fled war or poverty be sent back to Turkey unless they apply for asylum. For every person sent back, the EU would take in one Syrian refugee, thus trying to discourage them from the dangerous sea journeys, often arranged by unscrupulous smugglers.

But that complex and unclear agreement remained a concern for many, including human rights officials who questioned its legality.

"This agreement will dramatically reduce the legal entry points into the Union, forcing desperate refugees to look for other routes," warned Guy Verhofstadt, the leader of the liberal ALDE bloc in the European Parliament. He said people will again try crossing the Mediterranean, or go through Bulgaria and Albania.

Officials in Serbia said about 150 people are arriving each day via a dangerous trek through Bulgaria, with frequent reports of robberies and beatings by locals.

"This will be a major win for smuggling groups," said Tuesday Reitano of the Global Initiative against Transnational Organized Crime, referring to the EU-Turkey deal. "The effects are already visible."

Groups of 50 or more already are reported to have been smuggled through Albania, Reitano said. Clandestine routes are opening again in Hungary, where authorities report more people are breaching the razor-wire fence on its southern border.

Italy fears many may head west to Albania and use boats to cross the Adriatic Sea.

Frontex, the EU's border agency, said contingency plans are underway for any big shifts in migrant movements, with the organization's deputy executive director, Berndt Korne, naming Albania, the western Greek coast and Montenegro as possibilities.

Once spring arrives and the weather improves, people also could turn back to the dangerous route across the Mediterranean from Libya to Italy. Thousands have died off the Italian island of Lampedusa in recent years on that crossing.

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Jahn reported from Vienna. Lorne Cook in Brussels and David Rising in Berlin contributed to this report.