The captain of the Costa Concordia was not under the effects of drugs when the liner hit a rock that tore a hole in the hull and caused it to capsize near the port of Italy's Giglio island, his lawyer said on Monday.

A toxicology report showed that Captain Francesco Schettino had tested negative for drugs, his lawyer Bruno Leporatti told reporters. We had no doubts about it, Leporatti said.

The comment came as divers resumed a search for bodies on the stricken vessel, which lies on its side in about 20 metres of water off Giglio.

Thirteen people are known to have died and around 20 are still missing from the accident, which occurred in calm seas and good weather as the 114,500 tonne liner approached the island, apparently to make a display known as a salute.

Schettino has been charged with multiple manslaughter and abandoning ship before the evacuation of more than 4,200 passengers and crew was complete.

He is currently under house arrest in his home town of Meta di Sorrento near Naples.

(Reporting by Silvia Ognibene, writing By Steve Scherer)