The chief executive of one of Britain's leading banks, Barclays, has resigned in a move that has surprised financial analysts and led to a sharp fall in its shares.

A statement released by the bank did not explain why the executive, Martin Taylor, had quit, but a spokesman said the company had not sought his resignation.

Mr Taylor, who is forty-six, held the job for five years.

He is reported to be an ally of the governing Labour Party and is head of the government's task-force on Welfare Reform.

City analysts say Mr Taylor's resignation follows a warning of low profits from Barclays, which has lost large sums on Russian and Far Eastern markets and on its investments in the crisis-ridden American hedge fund, LTCM Long Term Capital Management.

Barclays also lost more than one-thousand-million dollars when it sold its equities arm, BZW.