Aon, the London offshoot of the world's biggest insurance company, was today fined £5.2 million for failures in preventing bribery and corruption, after it was found to have made suspicious payments worth millions of pounds to foreign firms and individuals.

The fine, which would have been £7.5 million if Aon had not pleaded guilty and agreed to pay up quickly, is the largest financial crime-related fine ever imposed by the Financial Services Authority (FSA).

Over three years from 2005 to 2007 Aon made 66 suspicious payments totalling almost $7 million (£4.5 million) to firms or individuals in Bahrain, Bangladesh, Bulgaria, Burma, Indonesia and Vietnam.

Four years ago Aon reached a $190 million settlement with New York Attorney General Eliot Spitzer over payments it had made to win business from insurance brokers in the US.

Aon's board includes some of the City's best-known names, including former top fund manager Paul Manduca, Ron Amy a former chairman of the National Association of Pension Funds, and is chaired by Steve McGill, former chief
executive of Jardine Lloyds Thompson.

Aon was fined £300,000 by Lloyds' Disciplinary Board for similar failings in preventing the payment of bribes in 2000. But even when Aon prepared for the shift from regulation by Lloyds to the FSA it failed to set up adequate systems to assess potential bribery or corruption.

But the FSA also praised Aon today after it blew the whistle on itself in 2007 when it told both the FSA and Serious Organised Crime Agency about the suspicious payments. The FSA said its response and determination to improve its systems and controls were “a model of best practice”.

While today is believed to signal the end of proceeding against Aon in this country it is still being investigated by the SEC and Department of Justice in the US.

It is also not clear whether or not there could be criminal proceedings against individual current or former employees in this country.