Indian seafarers have questioned the US military’s claim that it warned the crew of an oil tanker before launching an airstrike that killed three of them, saying that they had no reason to deliberately ignore or challenge American forces.

The US military’s Central Command, or Centcom, reported last week that an aircraft fired precision munitions into the engine room of MT Settebello after its crew failed to comply with orders to stop, disabling it in the Gulf of Oman.

Centcom accused the vessel of violating its “ongoing blockade by attempting to transport oil from Iran”.

Manoj Yadav, general secretary of the Forward Seamen’s Union of India, disputed Centcom’s version of the incident, telling The Independent that it was unlikely the crew would ignore warnings from military forces.

“I don’t think the crew would knowingly ignore any repeated military warnings,” he said. “Being a sailor, I know that when even a small boat comes alongside our vessel, people are scared that maybe pirates have arrived. And if warnings are coming from the US, and they are saying they fired 70 or 80 rounds before that, I don’t think anyone has the guts to simply ignore them and carry on.”

According to Centcom, American forces attacked Settebello only after it ignored repeated warnings.

Mr Yadav argued that if the ship had been moving under its own power, thermal imagery would likely have shown disturbed water or a visible wake behind the propeller.

No such disturbance was visible in the footage of the incident, he noted, suggesting that the ship was drifting rather than actively navigating.

“The biggest challenge was whether the vessel was moving. Was the vessel moving or was it drifting or was it at anchorage? Even in the thermal imagery Centcom released, you can see the vessel is drifting,” he said.

“Smoke is coming from the funnel but the vessel is drifting. If you look properly, you will not see water behind the propeller in the thermal view.”

He said it was hard to argue the vessel posed an immediate threat or was deliberately challenging the American forces enforcing a blockade of Iran.

“The three seamen died a very painful death,” Mr Yadav added. “Look at their mortal remains, and you will be able to analyse what kind of situation they must have gone through.”

The Independent has reached out to Centcom for comment.

The union leader condemned the US military’s decision to strike the engine room of the vessel, noting that it created an unnecessarily high risk of casualties. The engine room, he was, was directly beneath the crew accommodation area.

The attack suggested an intention to “hit the vessel and hit it hard”. If the objective had been to compel compliance, the military could have targeted less critical parts of the ship in a way that reduced the risk of casualties, he reasoned.

“If even a small tank had exploded inside the engine room, it would have been enough to destroy the entire accommodation,” he said.

Settebello was one of three vessels crewed by Indian sailors that was attacked by American forces this month after MT Marivex and MT Jalveer.

The killing of three Indian sailors on Settebello and the death of a fourth, Nishanth Uirthanathan, 35, reportedly from medical complications exacerbated by a delay in his evacuation from MT Celestial, a tanker docked at an Oman port, sparked public anger in India, especially after Washington refused to apologise for the attack.

“It was murder and it has to be recognised by the UN as well,” Mr Yadav said.

The attack on the seamen also caused a strain in India-US relations. India’s foreign ministry condemned the “attack on the commercial vessel” and lodged a “strong protest” with the US deputy chief of mission in Delhi.

Foreign minister S Jaishankar said “such lethal actions against commercial shipping are not justified”.

The opposition criticised prime minister Narendra Modi for staying “silent” over the deaths of Indian sailors.

“Foreign powers kill our citizens. Our government quietly obeys orders like an obedient servant and our citizens are left to rot,” Rahul Gandhi, the leader of the main opposition Congress party, said.

After Mr Modi flew to attend the G7 summit in France, the Congress criticised him for going on “jaunts” while the families of the sailors were mourning their deaths.

“He is watching song and dance in France and has no concern for his own country at all. Narendra Modi’s silence on these painful deaths and his government’s cowardly attitude is an example of the country’s failed foreign policy,” it said.

Mr Yadav said his union had demanded compensation for the deaths of four sailors. “A peace agreement has been announced. We will see whether it’s fully implemented. In the meantime, we have made one demand: the US must compensate the families of all these people because they were in international waters and had nothing to do with this war,” he said.

“Their deaths were not natural deaths. They were not caused by a mechanical accident. They did not die because of something that happened in their workplace. They were simply murdered by the US.”

In the case of the MT Celestial sailor, My Yadav said it took “a lot of pressure from the media and social media before the vessel was finally allowed to come ashore”.

“The same thing that happened now could have happened two days earlier, and perhaps this man’s life could have been saved,” he said.

The union said it was contemplating legal action if their demands were not met. “We’ll take it up with the UN after discussions,” he said. “We’ll take it forward for sure.”

Mr Yadav said that the US-Israeli war on Iran had been traumatic for Indian seafarers, nearly 18,000 of whom were working in the Middle East. “It was a really pathetic situation. We have received letters from crew members on the remaining ships saying they all want to sign off. They are not mentally fit, and they all want to go home,” he said.