Three Indian seafarers are missing after Oman rescues 21 others following a US attack on the Palau-flagged Settebello.

India has summoned a senior US diplomat after US forces fired on a Palau-flagged vessel with 24 Indian sailors on board off the coast of Oman, leaving three Indian seafarers missing.

India’s Ministry of Foreign Affairs confirmed to Al Jazeera on Wednesday that it had summoned Jason Meeks, the US Embassy’s deputy chief of mission in New Delhi.

The US military’s Central Command (CENTCOM) said it carried out a “precision” strike on a vessel, the Settebello, as it transited the Gulf of Oman transporting Iranian oil on Tuesday evening, claiming the crew failed to comply with instructions from US forces.

The ship was a chemical/oil products tanker which reported an engine room fire 20 nautical miles (about 37km) northeast of Oman’s port of Sohar, the United Kingdom Maritime Trade Operations agency said.

The Omani navy responded to the Settebello distress call, British maritime risk management group Vanguard said.

Twenty-one Indian sailors have been rescued and three remain missing, India’s Foreign Ministry said, condemning the violence and calling for an end to attacks on commercial shipping and civilian infrastructure in the region.

“Our embassy in Oman is closely monitoring the situation and proactively coordinating with the Omani authorities in the ongoing search and rescue operation,” the ministry said in a statement. “The targeting of commercial shipping and civilian infrastructure in the region must end.”

Arsenio Dominguez, secretary-general of ‌the ‌UN’s shipping agency, the International Maritime Organization, on Wednesday condemned “any act from any party that endangers the lives of seafarers and the safety of international shipping”.

“This is simply unacceptable. My thoughts are with the families of the three missing seafarers and with all those awaiting news of the crew members,” he said.

The incident has intensified legal and ethical questions surrounding the US naval blockade of Iran, which has negatively affected Washington’s allies. It could also further damage India-US ties, which experts say are already at their lowest point in decades.

Pressure from opposition

The Indian government was under mounting pressure from the opposition to publicly challenge the US over the strike, after it failed to protest against a separate attack by US forces on a vessel carrying Indian sailors earlier this week.

Since the US-Israel war on Iran began on February 28, at least two other Indian-flagged vessels have been struck. India summoned the Iranian ambassador in April in response to the attacks.

President Donald Trump ordered a naval blockade of Iran in mid-April in an attempt to force Tehran to accept his terms for a deal to permanently end the war.

The blockade is believed to have significantly reduced Iran’s oil exports, though Iranian officials have shown no sign of capitulating to Washington’s demands.