An Indian crew member of a ship docked at an Omani port died from medical complications, reportedly after a delay in his evacuation.

The Forward Seamen’s Union of India claimed that Nishanth Uirthanathan, 35, from the southern state of Tamil Nadu died aboard the tanker MT Celestial while it was docked at Duqm Port.

The union said Uirthanathan died at around 6pm local time on 11 June after “falling seriously ill” three days earlier.

“His body has remained onboard for over two days with no proper refrigeration,” it said. “Crew is using cold water bottles in a desperate attempt to slow decomposition – a horrifying and health-risking situation. Despite repeated distress calls, timely medical evacuation was reportedly delayed amid regional tensions.”

The union called for urgent preservation and repatriation of the sailor’s body, support for the crew and “full investigation into the response failures.”

The Independent has reached out to the union for comment.

The Indian embassy in Muscat confirmed the death. “The embassy remains in active coordination with local Omani authorities, port officials, and the shipping company regarding Mr Nishanth Uirthanathan, who unfortunately died onboard MT Celestial due to medical conditions,” it said.

It said arrangements had been made “for prompt recovery of the mortal remains from the vessel.” “The concerned Omani authorities are scheduled to board the vessel to complete the necessary procedures for disembarkation of the mortal remains,” it added.

MT Celestial was stopped by the US military for a search drill last month on suspicion of violating its blockade of Iran, but released with orders to alter course.

“Earlier today in the Gulf of Oman, US marines from the 31st Marine Expeditionary Unit boarded MT Celestial, an Iranian-flagged commercial oil tanker suspected of attempting to violate the US blockade by transiting toward an Iranian port. American forces released the vessel after searching and directing the ship’s crew to alter course,” Centcom said in a statement on 20 May.”

Uirthanathan’s death comes amid growing concern among thousands of Indian seafarers stranded in the Gulf region.

According to India’s shipping ministry, Indian seafarers across the global shipping fleet number about 300,000, with more than 18,000 employed in the Middle East.

At least 13 Indian-flagged cargo ships carrying 562 Indian sailors remain stranded in and around the Strait of Hormuz. According to the shipping ministry, 329 sailors are aboard vessels stranded west of the strategic waterway and 233 are on ships stuck east of the strait the Gulf of Oman.

Uirthanathan’s death was confirmed days after three Indian crew members of the tanker MT Settebello were killed in a US ​military attack in the ​Gulf of Oman.

The US claimed the vessel, sailing under the Palau flag with 24 Indian sailors, ignored some 60 warnings from its forces before it was struck, Associated Press reported.

The seamen’s union demanded the US pay “fair compensation of not less than $5 million” to the families of the three seafarers killed in the attack as well to the family of Uirthanathan. “Justice for the victims is key to lasting peace,” it added.

In the aftermath, the directorate general of shipping issued an advisory for Indian sailors in the region. “In view of the heightened security situation in the Gulf region, Indian seafarers, shipowners, managers, and maritime stakeholders are advised to exercise maximum vigilance and strictly follow all security advisories. The safety and welfare of Indian seafarers remain our highest priority,” it said.

Sarbananda Sonowal, the minister for shipping, said the government was monitoring the situation in the Gulf region and was “fully committed to the safety, security and welfare of every Indian seafarer”.

“All relevant ministries, agencies and missions abroad are working in close coordination to ensure timely support and assistance whenever required,” he said.

The opposition questioned prime minister Narandra Modi’s silence on the attacks on Indian seafarers. “Three Indians have been killed in U.S. attacks on three ships in international waters within three days. And our compromised PM,” Rahul Gandhi, leader of the main opposition Congress party wrote, “not a single word.”

“When any foreign power murders an Indian, the prime minister has to speak up. But he can never utter even one word.”

Mr Gandhi said “America has continued issuing orders” and Mr Modi has remained “silent” and listened “like an obedient servant”.