The families of three Indian seafarers who were killed during an attack on an oil tanker in the ​Gulf of Oman have demanded the US “take responsibility” and pay $5m compensation for the deaths of their loved ones.

Shivanand Chaurasiya, Patnala Suresh and Aditya Sharma were part of the crew of the Palau-flagged MT Settebello, and died when the US opened fire on the ship’s engine room to disable it.

The US military claimed that the vessel ignored some 60 warnings before it was struck. But a major Indian seafarers’ union has rejected the claim, arguing the crew had no reason to deliberately ignore or challenge American forces.

The sailors’ deaths have made headlines in India for weeks, and threatened to overshadow Donald Trump’s talks with Narendra Modi on the sidelines of the G7 summit in France. Mr Trump offered no apology when questioned during the meeting, only noting that sailing is a “rough profession”.

On Monday, the families of the dead sailors said the world should not forget them, as they called on the US to be held accountable for actions that resulted in the loss of innocent lives. They said the seafarers had nothing to do with the US-Israeli war on Iran.

The seafarers’ union has demanded the US pay “fair compensation of not less than $5m” to the families of the three seafarers killed in the attack as well as to the family of another Indian seafarer, Nishanth Uirthanathan, who died from medical complications in the Persian Gulf reportedly after a delay in his medical evacuation.

“Justice for the victims is key to lasting peace,” it added.

The family of Shivanand Chaurasiya said they only learned about the fatal strike from a relative in Dubai. “The US government should take responsibility for it,” the late sailor’s father, Rampravesh Chaurasiya, said.

“The Indian government should demand from the US government that the three mariners who died should be compensated by the US government.”

Patnala Bala B, the wife of the Settebello’s chief engineer Patnala Suresh, said she had spoken to her husband the evening before his death and he had reassured her that everything was fine despite reports of attacks on vessels in the region.

“The previous night at around 8.30pm, he told me it was all fine,” she said. “The next morning it happened. They told us he was just missing. The next day, at around 2pm, they announced he was no more.”

She said Suresh was the family’s sole breadwinner. “He loved India. He loved machinery. That was his passion,” she said.

The body of the seafarer who died from medical complications finally arrived in India on Wednesday. The Omani authorities had reportedly said that they would bury the remains there if his repatriation was not completed by 25 June.

Nishanth Uirthanathan, 35, died on 11 June aboard the MT Celestial while it was docked at the Duqm port in Oman. Rebecca Sarobin said that her husband had boarded the tanker in good health but taken ill while at sea.

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

Ms Sarobin claimed the shipping company failed to promptly inform the family about her husband’s health condition and death, leaving them to rely on his crewmates and friends instead. The Romana Shipping Company had earlier rejected suggestions of any wrongdoing, according to Mathrubhumi News.

Ms Sarobin, mother to two children aged 3 years and 8 months, said her husband’s loss was unbearable.

“I need justice for my husband’s death,” she said on Monday. “Why do Indian seafarers have to risk their lives? That’s my question.”

She said now that her husband was no longer with them, she would struggle to support her family. “I have a three-year-old child and an eight-month-old baby. All I want is long-term support, for my future and for my children’s education,” she said.

Rajesh Sharma, the father of cadet Aditya Sharma, called for a thorough investigation into the US attack on the Settebello as well as into the ship’s management. They “should be held accountable and punished”, he demanded.

He alleged the vessel had continued sailing towards the Strait of Hormuz despite warnings and called for an investigation into the circumstances surrounding the attack. The Independent could not verify the claim.

“I had only one son. I have no other son, no daughter now. My aim is to provide justice to Aditya Sharma. I will go to any extent for this purpose only,” he said.

India’s director general of shipping (DGS), Shyam Jagannathan said the issue of Indian seafarers’ safety was raised at the G7 by Mr Modi during “one-to-one parlays with [Mr Trump]”.

Mr Jagannathan said the families of the deceased seafarers had “every right to move for compensation under US law and also under international (maritime) law”.