The Italian and Swiss firms are among those which could make bids of about £6billion for the two general insurance businesses by today’s informal deadline.

Others said to be keen are Germany’s Allianz Group, with the Bank of China and Chin­a’s Ping An also said to be mulling over a bid.

A sales memorandum has been sent to eight companies but one, Warren Buffett’s Berk­shire Hathaway, has already pulled out.

Sources said private equity companies might be interested, although none have been sent the memorandum.

It has been said RBS’s advisers, Gold­man Sachs and Merrill Lynch, have barred private equity firms from bidding because of concerns about whether they could raise the cash in the current shell-shocked debt mar­kets.