An “unprecedented” crisis is unfolding for 20,000 seafarers stranded in the Persian Gulf, a UN body has warned, as the Strait of Hormuz closure leaves crews trapped on ships with no clear way out.

As the stalemate in the Gulf drags on, maritime workers – many from poor, developing countries – are finding themselves stranded at sea, caught between commercial pressure from ship owners, security threats from drones and sea mines and limited legal protections.

“It is an unprecedented situation,” Damien Chevallier, director of the Maritime Safety Division at the UN’s International Maritime Organization (IMO), said in an interview with CNN. “We have around 20,000 seafarers in the Gulf for now close to eight weeks. It is a humanitarian crisis. We have never faced such a situation.”

The warning lays bare the severity of the situation facing the crews. Many are unable to dock on either side of the Persian Gulf: Iranian ports pose war-zone risks, while visa restrictions and logistical hurdles along the Arab states lining the Gulf’s southern shores make it difficult for many sailors to leave their vessels. The maritime exit – through the Strait of Hormuz – remains effectively closed.

Since the war started, Iran has sought to impose new navigation rules in the Persian Gulf, allowing vessels from so-called “friendly” countries to pass through the strait in exchange for fees.

In response, the Trump administration has moved to enforce a naval blockade targeting ships entering or leaving Iranian ports and warning shipping firms they could face sanctions if they pay those tolls.

The competing measures have created a standoff that has brought traffic through the strategic chokepoint to a near halt, with only a handful of vessels transiting the waterway each day compared to more than a hundred in normal conditions.

Hundreds of vessels are now seeking a way out of the war-torn area.

“Around 800 to 1,000 vessels would like to sail through the Strait of Hormuz to evacuate the area,” Chevallier said.

One such case is the Auroura, a sanctioned oil tanker linked to Iran’s shadow fleet of vessels used to transport oil in defiance of American sanctions.

Crew members told CNN in an interview last month that they had been stranded onboard for weeks after the war broke out, requesting repatriation after they say the ship’s owner pressured them to sail to Iran to pick up oil despite mounting risks.

The vessel’s crew, all Indian nationals, described worsening conditions onboard, including shortages of food and fresh water.

Manoj Yadav, a union organizer with the Forward Seamen’s Union of India, said the situation was dire.

“The crew is facing shortages of basic supplies,” he told CNN at the time. “They want to go back home. The situation on this vessel is not good.”

The Auroura is far from an isolated case, according to the International Transport Workers’ Federation (ITF), a global trade union that represents seafarers around the world.

“It’s not only repatriation, it’s abandonment,” said Mohamed Arrachedi, the ITF’s flag of convenience network coordinator for the Arab world and Iran. “Some seafarers have not been paid for eight or even 11 months.”

Arrachedi described widespread reports of intimidation and pressure from shipowners.

“There are a lot of cases of intimidation. Some shipowners just get furious,” he said. “I have cases where seafarers are verbally threatened.”

The crew of the Auroura allege they were threatened with withheld wages and warned of “serious consequences” if they refused to sail to Iran and load oil.

“He said we are hijacking his vessel… sabotaging his vessel,” one crew member told CNN, describing accusations made by the ship’s owner.

CNN has reached out to the ship’s management for comment but has not received a response.

The crew said they repeatedly requested sign-off and repatriation, a right protected under international maritime law, including in situations where safety is compromised, but were denied.

“Despite repeated requests, the company has refused to arrange our sign-off or repatriation,” they wrote in a March 13 incident report to maritime authority the United Kingdom Maritime Trade Operations (UKMTO), reviewed by CNN. “We are effectively stranded onboard under unsafe conditions.”

Those fears have increasingly become reality. At least 10 seafarers have been killed in attacks on shipping since the war with Iran began, according to IMO.

“I have cases where seafarers are telling me they are sleeping with their clothes on, just in case they are attacked,” Arrechedi said. “Families are anxious, asking us what is happening.”

On March 13, while anchored off the coast of the United Arab Emirates, the Auroura was struck by drones, according to crew members and security footage reviewed by CNN.

“It was totally dark,” said one crew member. “Suddenly there was an explosion. And then we saw debris lying here and there.”

Video shows an explosion tearing across the deck near the bridge, narrowly missing a crew member on watch. Images also show damage to one of the vessel’s lifeboats, potentially rendering the ship non-compliant with international maritime safety regulations.

In the incident report to UKMTO, crew members described the attack as an immediate threat to life.

“One deck cadet narrowly escaped loss of life during bridge watch,” the report states.

The ship finally sailed through the Strait of Hormuz to Oman on April 14, ship tracking data shows, hours before Trump’s deadline to impose a blockade on Iranian ports.

After weeks stranded at sea, some sailors aboard the Auroura were finally allowed to leave the vessel.

Seven sailors were signed off and replaced by a new Pakistani crew, according to one seafarer who requested anonymity to avoid retaliation. He said they flew from Oman to India between April 26 and 27.

For maritime officials and labor groups, the Auroura is one example of a much wider crisis unfolding across the Gulf.

Captain Isdik Alam, a sailor working aboard another ship in the Persian Gulf, described to CNN deteriorating conditions on other vessels stranded in the region.

He said some crews have been forced to reuse water from air-conditioning systems to wash clothes and, in some cases, even to prepare food.

“We are unable to wash our clothes or take a shower,” he said. “They are collecting water from the air-conditioning drains just to wash and survive.”

Alam described a growing sense of abandonment among seafarers caught in the crisis.

“Nobody is caring about seafarers,” he said. “Ceasefire or no ceasefire, it is not for us.”

While sailors are trained to endure harsh conditions at sea, he said the threat they now face is fundamentally different.

“I am not a warrior. I am a seafarer,” he said. “I’m not scared of the sea… I’m scared of missiles and attacks.”

CNN’s Isobel Yeung contributed to this report.