India lets Iran warship dock the day US sank another off Sri Lanka

India has allowed an Iranian warship to dock as a "humanitarian gesture", Foreign Minister Subrahmanyam Jaishankar said on Saturday, after the US sank another Iranian navy vessel off neighbouring Sri Lanka.

The Lavan docked at India's southern port of Kochi on Wednesday, the same day the US submarine struck Iranian navy frigate Dena, after an urgent request from Tehran, an Indian Government source told Reuters.

US President Donald Trump has said destroying the Iranian Navy is one aim of the war he and Israel launched against the authoritarian state a week ago.

The Lavan - an amphibious landing vessel, according to the US Naval Institute's online news site - and two other ships, "were coming in for a fleet review and then they got, in a way, caught on the wrong side of the events," Jaishankar told the annual Raisina Dialogue event.