United Nations: A top UN official has called for a thorough investigation into the weekend luxury cruise ship disaster off the coast of Italy that left six people dead and at least 15 missing.

Secretary-General of the UN body International Maritime Organization (IMO) Koji Sekimizu said the Costa Concordia accident cannot be taken "lightly" and prompts a re-look at the safety regulations of large vessels.

"We should seriously consider the lessons to be learnt and, if necessary, re-examine the regulations on the safety of large passenger ships," a statement from the UN agency quoted Sekimizu as saying on Monday.

He added that an investigation "covering all aspects of this accident" should be carried out, findings of which should be provided to IMO as soon as possible.

"Causes of this accident are still not yet established," he said.

"We must wait for the casualty investigation and should not pre-judge or speculate at this stage."

Six persons died and at least 15 are still missing after the Costa Concordia ran aground on Friday near Giglio Island, conjuring memories of the 1912-Titanic shipwreck.

A total of 4,200 passengers and crew were on board the vessel. There were a total of 203 Indians on the ship – one passenger and 202 crew members.

Out of the 202 Indian crew members, 201 have been traced and are safe. One person is missing.

Sekimizu expressed condolences and sympathy to the families of those who lost their lives in the tragic incident.

"In the centenary year of the Titanic, we have once again been reminded of the risks involved in maritime activities," he said.

The IMO, based in London, is the UN specialized agency with responsibility for the safety and security of shipping and the prevention of marine pollution by ships.