Cruise liners acting as floating hotels during the Olympic Games in Athens next summer might not be able to find insurance cover due to fears they would be easy targets for terrorists, according to a report.

Eleven ships, including the world's largest cruise liner, the Queen Mary 2, would be used as hotels due to a shortage of accommodation in the city, revealed the report. The ships, which provide 6,500 cabins at five, four and three star standard, would dock at the Port of Piraeus.

The report said the majority of the vessels had insurance to cover them in case of an accident, but in the next fortnight brokers would start looking to place cover for damage caused by war or acts of terrorism.

It said underwriters were taking a hard stance as they were seriously worried about insuring the ships.

Kiln's director of marine risks at Lloyd's, Charles Franks, said: "There are concerns because of the concentration of high-value cruise ships in a single location and the high-profile nature of the event. In this climate, terrorism is an obvious concern."

The value of the cruise ships concerned was a major consideration for underwriters, revealed the report. The Queen Mary 2 cost an estimated US$800m to build. It can hold up to 2,620 passengers and 1,250 crew. It has been insured for $780m, with Royal & SunAlliance taking the lead.

According to the report, specialist intelligence company Exclusive Analysis, which advises Lloyd's underwriters of war, terrorism and political risks, said insurers were right to be concerned.

Managing director Simon Sole said: "The Greeks are seriously behind schedule in terms of security preparation and they have not given appropriate information which would allow people to be reassured."

A spokesman for the Athens organising committee for the Olympic Games said the Greek government had a budget of €650m for security infrastructure and would have a trained security force of more than 41,000 in place by the time of the games, concluded the report.