In a message on Sunday, Ayatollah Khamenei offered condolences to the bereaved families of the 32 crew members of the Iranian oil tanker who lost their lives in the "calamitous and regrettable" incident.
The Leader said the sailors sacrificed their lives as they were fulfilling their duty for their country.
The Sanchi oil tanker, carrying 136,000 tonnes of condensate from Iran to South Korea, caught fire on January 6 after it collided with the CF Crystal, a Hong Kong-registered bulk freighter, about 160 nautical miles (184 km) off China's coast near Shanghai.
Iranian officials said on Sunday that the vessel had completely sunk and available evidence indicated that all crew members had died soon after the collision and a powerful blast.
Thirty two crew members were on board, comprising 30 Iranians and two Bangladeshis. A Chinese salvage team on Saturday recovered two bodies from the tanker. Another body, presumed to be one of the Sanchi's sailors, was found on Monday and brought to Shanghai for identification.
Iran's President Hassan Rouhani and Foreign Minister Mohammad Javad Zarif issued separate messages of condolences over the death of sailors on board the Iranian oil tanker.
The Iranian Cabinet declared Monday, January 15, as a nationwide day of public mourning over the tanker disaster.