THE activist investor who is pushing for a strategic shift at Barclays has hit back at the bank's directors after they urged shareholders to oppose his appointment to the board.

Edward Bramson, who holds a 5.5 per cent stake in Barclays through his investment vehicle Sherborne, said the board must adopt a "more realistic and shareholder oriented" strategy.

He was responding to a statement issued last week in which the firm's directors argued that it was not in need of a strategic overhaul.

Mr Bramson has been an outspoken critic of the firm and has called for its corporate and investment banking arm to be shrunk.

Writing to fellow shareholders on Monday, Sherborne said an alternative voice on the board would be "healthy" and urged investors to back Mr Bramson's appointment.

"It seems to us that a board comprised of twelve or more senior business people should be able to accommodate and resolve occasional differences of perspective and arrive at better and more sustainable outcomes for shareholders than a board that cannot," it said.

"An alternative voice on the board would seem to be healthy for the company and its shareholders."

Responding to the board's claim that Mr Bramson does not have appropriate banking experience, the letter said: "By our count, five of the current directors already have banking or advisory backgrounds and we wonder how adding more could possibly make any substantive difference."

The letter also referenced reports that Tim Throsby, former head of the corporate and investing arm, clashed with Barclays chief Jes Staley over the "irreconcilable" gap between goals set by the board and targets for investor returns.

Sherborne said it hoped a warning of this nature would increase the board's awareness that the current strategy is placing "unreasonable demands on management".

The annual meeting will take place on May 2, when shareholders will vote on whether to appoint Mr Bramson to the board.