Up to 600 Aon staff are believed to have been involved in the World Trade Centre collapses in New York earlier today.
It is also feared that employees of Marsh, Guy Carpenter and Scor have been injured in the disaster. The companies had offices in the towers, which have a leasehold value of £1bn.
A Boeing-737 and a light aircraft crashed into the World Trade Centre in New York earlier today. It is also reported that another plane crash has caused the collapse of the Pentagon in Washington DC, while the White House, also in Washington, has been evacuated.
Other reports say eleven Boeing-767s have been hijacked.
A spokesman for Marsh confirmed that the firm has offices in the World Trade Centre but was unable to comment on whether employees have been affected. It is believed that Marsh's offices were on the 90th floor of the building while Aon's were situated on the 105th floor.
Lloyd's underwriters are investigating liabilities following the plane crashes.
The Democratic Front for the Liberation of Palestine has claimed responsibility for the attacks.
