A spokesman for the former prime minister confirmed that he had agreed to give a number of private talks to executives at the Mayfair-based Lansdowne Partners.

The fund is reported to have made millions of pounds from the credit crunch betting that stocks in banks like Barclays and Northern Rock would fall.

One of the firm's founders, Paul Ruddock, is a Conservative Party donor.

No details were available of Mr Blair's fee for the talks which were arranged through the agency which organises his speaking engagements.

The former prime minister already works as an adviser to the US investment bank, JP Morgan, and Zurich Insurance, although his spokesman stressed that he was not taking on a permanent role at Lansdowne.

"Mr Blair remains one of the most popular international speakers around. These talks for Lansdowne were organised by the Washington Speakers Bureau in the usual way. Mr Blair has not taken a job with Lansdowne Partners," the spokesman said.

The disclosure comes as Mr Blair is once again in the spotlight as he prepares to give evidence to the Iraq Inquiry on Friday.