Barclays chief executive Bob Diamond has resigned with immediate effect, the bank said today.

The move comes after Barclays was fined �290 million by UK and US regulators for manipulating the Libor, the rate at which banks lend to each other.

Mr Diamond said: “The external pressure placed on Barclays has reached a level that risks damaging the franchise.”

The bank’s chairman Marcus Agius, who announced his intention to resign over the affair yesterday, will lead the search for a new chief executive immediately, Barclays said.