Billionaire investor Warren Buffett will be interviewed in New York today by US investigators who are examining controversial reinsurance contracts booked in the Dublin unit of his General Reinsurance group.

The investigation into a $500 million reinsurance contract with AIG, the world's biggest insurer, has cast international attention on General Re's low-profile operation in the IFSC, which trades under the name Cologne Re.

Its activities are also the subject of an investigation by Ifsra, although news of the Irish regulator's examination emerged publicly only after US regulators let it be known that they were investigating the Dublin office.

Unknown to most people in Dublin's financial community, some of Cologne Re's activities in the IFSC were linked by Australian regulators to the collapse in 2001 of Australia's second biggest insurer, HIH.

The US investigation could prompt a wider inquiry into the global reinsurance industry, which has a major presence in the IFSC. Some 195 firms there have annual premiums in excess of €10 billion.

Mr Buffett is said to be co-operating with officials from the Securities & Exchange Commission and the office of the New York attorney general, Eliot Spitzer.

US regulators have said that he is likely to be asked about transactions that were booked in General Re's "global solutions group" in Dublin.

At issue is whether the transaction in question was used to create the impression that AIG's books were stronger than they really were.

The US regulators want to find out whether the effect of the transaction booked in Dublin was to negate the element of risk in the reinsurance transaction.

If that was so, the transaction should have been treated as a loan between the companies with the money in question added to AIG's debt instead of its reserves.

While Mr Buffett has denied any knowledge of the deal, the affair has already led AIG to oust its long-serving chief executive and chairman, Maurice "Hank" Greenberg.

AIG has restated its books in a move which it said could cut its net worth by $1.7 billion or 2 per cent.

Mr Greenberg will be interviewed tomorrow by US investigators.

According to the Wall Street Journal, Mr Buffett tipped off US regulators to the AIG deal in an attempt to win leniency in an unrelated case, which is still under way.

The transactions under scrutiny in the US are broadly similar to those identified by Australian regulators in their investigation into what was Australia's biggest corporate collapse.

HIH's failure followed its acquisition of another Australian insurer, FAI, whose weak financial position was disguised by a reinsurance transaction with General Re which was linked to the Dublin office.

The Australian regulators moved last October to disqualify two Dublin-based Cologne Re officials from working as directors or senior managers in the Australian industry.

Both individuals are appealing this decision, although one of them, Tore Ellingsen, left Cologne Re last week.

The other, John Houldsworth, was said to be "in a meeting" when The Irish Times tried to contact him at Cologne Re's IFSC office last Friday.

A former chief executive of Cologne Re in Dublin, he has made no public comment on the investigation.