Sri Lanka's maritime authorities were monitoring a fleet of 11 US-sanctioned Iranian oil tankers just off the island's southern coast, officials said Wednesday.
The vessels are in limbo -- they cannot return to Iran because of a United States blockade on ships using Iranian ports.
The ships were spotted close to the Galle harbour where an Iranian frigate, IRIS Dena, was sunk by a US submarine in March, killing 104 sailors. Sri Lanka's navy rescued 32 Iranian sailors from that frigate.
"We have deployed reconnaissance aircraft and patrol boats to monitor these Iranian vessels outside our 12-nautical-mile territorial waters," a military official told AFP on condition of anonymity.
The vessels had not sought permission to enter Sri Lankan territory and were entitled to freedom of navigation in international waters.
"There is no indication of any ship-to-ship transfer of oil or illegal discharge of pollutants, so there is no basis for Sri Lankan authorities to take action against them," he said.
Many Iranian merchant vessels moved east towards the Strait of Malacca and Singapore after the US sanctions, while several remained near Sri Lankan waters, authorities said.
Sri Lankan officials said Washington had not formally notified Colombo about sanctioned Iranian-flagged vessels.
