A statement from the external affairs ministry that condemned Wednesday’s attack didn’t mention who was behind the strike, though people familiar with the matter confirmed the Palau-flagged tanker Settebello was targeted by US forces for reportedly trying to evade an American blockade of Iranian ports.

US chargé d’affaires Jason Meeks was summoned to the external affairs ministry by additional secretary (Americas) Nagaraj Naidu for lodging a strong protest, the people said on condition of anonymity. The Indian side made it clear that attacks that put the lives of Indian seafarers at risk are unacceptable, they said.

“We condemn the attack on the commercial vessel Settebello off the coast of Oman, earlier today. Of the 24 Indian crew on board, 21 Indians have been rescued thus far and 03 Indians are reportedly missing,” the statement said.

The Indian embassy in Oman is monitoring the situation and “proactively coordinating with the Omani authorities in the ongoing search and rescue operation”.

The Settebello, which was sailing from Lianyungang port in China to Fujairah in the United Arab Emirates (UAE), had a crew of 28, including 24 Indians, two Pakistanis, a Russian and an Ukrainian, the people cited above said. The Omani armed forces rescued 21 Indian crew members, they said.

The Settebello reported an engine room fire 20 nautical miles northeast of the Omani port of Sohar, the United Kingdom Maritime Trade Operations (UKMTO) reported on its website. British maritime risk management group Vanguard reported that Settebello transmitted a distress call about being struck by a missile that caused a fire, and that the Oman Navy responded to the tanker’s call.

Unlike Monday’s attack by US forces on the Palau-flagged tanker MT Marivex, New Delhi decided to condemn Wednesday’s assault as it resulted in three Indian crew members going missing, the people said. The US chargé d’affaires was summoned as ambassador Sergio Gor was on a visit to Kazakhstan.

The 24 Indians on board Marivex, which was sanctioned by the US, too were rescued by the Omani military. The US Central Command said it disabled the Marivex after it “violated the ongoing blockade against Iran”.

The external affairs ministry described the continuing attacks on shipping in the region as “deeply worrisome and a direct result of the ongoing conflict” in West Asia, and reiterated India’s call for a negotiated end to hostilities between Iran and the US.

“We reiterate our call for immediate de-escalation of tensions, and the conclusion of ongoing negotiations for a diplomatic solution so that peace and stability can return to the region,” the statement said. “The targeting of commercial shipping and civilian infrastructure in the region must end, and free and unimpeded navigation and commerce through the international waterways in the region in keeping with international law must be restored at the earliest.”

The US began a blockade of Iranian ports on April 13 after Tehran curtailed the passage of vessels through the Strait of Hormuz. The US Central Command reported on June 8 that American forces had disabled seven non-compliant vessels, redirected 134 others, and allowed 42 vessels supporting humanitarian aid to pass.

Ten Indians have died in West Asia since the conflict began in February, including three seafarers killed in attacks on merchant vessels in the early days of the hostilities.