Return of the Blair casts a shadow over Brown

Tony Blair is to co-host a summit on the global financial crisis with President Nicolas Sarkozy in January, in a move likely to infuriate Gordon Brown.

Mr Blair's office has been in in touch with the Prime Minister to invite him to the Paris conference, but Mr Brown has so far refused to accept the invitation, with an official saying last night he was still considering his "diary commitments".

Sources said that Mr Brown was "relaxed" about the event taking place. However, any attempt by Mr Blair to overshadow Mr Brown's efforts on the world stage is likely to anger Downing Street aides. He has rebuilt his political reputation by claiming to lead the world in tackling the global financial crisis – most recently with a "road map" for financial reform he presented at a G20 summit last weekend.

But he may now have to contend with Mr Blair taking on a formal role in the global response to the economic crisis.

The summit will come days before Barack Obama is sworn in as US President on Jan 20, and threatens to upstage a follow-up G20 summit that Mr Brown is expected to host in London in April.