The sailors from 19 ships were brought ashore at Galle Harbor, about 126 km from the commercial capital, Colombo, and were given medical treatment before returning to Iran early on Sunday morning.
Sri Lanka coordinated the rescue of 40 Iranian sailors from multiple commercial ships in international waters off the coast of the country and supported their return to Iran, a spokesman for the island nation's foreign ministry said on Sunday.
The ministry received a request from the Iranian embassy via diplomatic channels to rescue the sailors, Thushara Rodrigo, a spokesman for the ministry, said, adding they had been suffering unspecified medical emergencies.
The ministry didn't give any further details of why they had to be rescued, but local media, including the Indian national newspaper The Hindu, reported they were on board vessels that were US-sanctioned oil tankers.
Washington has imposed a blockade on Iranian shipping as part of its war on Iran.
The sailors from 19 ships were brought ashore at Galle Harbor, about 126 km from the commercial capital, Colombo, and were given medical treatment before returning to Iran early on Sunday morning, the spokesman added.
Sri Lankan navy provides humanitarian support to Iranian sailors
Sri Lanka's navy and coastguard typically provide support during humanitarian efforts, a government source with direct knowledge of the rescue told Reuters.
Earlier this year Sri Lanka rescued dozens of Iranian sailors on humanitarian grounds after the Iranian warship IRIS Dena was sunk by a torpedo from a US submarine on March 4.
The bodies of more than 80 sailors who died in the attack were flown back to Iran in mid-March. Thirty-two survivors of the sunken ship, as well as 208 crew members from another vessel, were returned to Iran in April.