Three Indian seafarers are still missing after 21 other Indian mariners were rescued following an attack on their tanker off the coast of Oman, India's foreign ministry said on Wednesday.

"We condemn the attack on the commercial vessel Settebello off the coast of Oman, earlier today," the ministry said in a statement.

"Our embassy in Oman is closely monitoring the situation and proactively coordinating with the Omani authorities in the ongoing search and rescue operation."

Maritime officials said the oil products tanker had been hit in a suspected U.S. missile strike.