The Panamanian Maritime Authority says it has dispatched an investigator to the scene of a fatal casualty between a Panama-flagged Iranian tanker and a Chinese bulker.

The registry's Marine Accident Investigation Department sent personnel to investigate the casualty occurring between National Iranian Tanker Co's 164,000-dwt tanker Sanchi (built 2008) and the Hong Kong-flagged 76,000-dwt CF Crystal (built 2011), owned by China's CoscoCS.

The Sanchi was heading towards South Korea from Kharg Island in Iran, the Panama registry said. Approximately 160 nautical miles from the coast of Shanghai, it collided with the CF Crystal, which was carrying grain.

Panama's minister for maritime affairs, Jorge Barakat Pitty, extended his condolences to the relatives of the 32 seafarers aboard the Sanchi, who are still missing.

"The Panamanian Registry expressed its concern from the first moment about the situation of the ship and is looking for the best solution to this marine disaster, taking into account the protection of the marine environment and climatic conditions that prevail in the place where the incident occurs," the registry said in a statement.

The registry said it is working with international authorities to investigate the cause of the accident and issue recommendations to try and prevent similar accidents from occurring in the future.