Time Warner's plush HQ is one of Carl Icahn's pet hates

In a letter to shareholders, Carl Icahn said 12 of the 15 board members had backed a merger with internet firm AOL - which cost the firm 75% of its value.

A string of other mis-steps meant it was in shareholders' interest to get rid of the board members, he added.

Time Warner said its current plans, and management, would remain intact.

'Cardinal sins'

Mr Icahn now wants a seat on the Time Warner board and is supported in his campaign by three hedge funds which between them hold 2.8% of the shares in the $84bn firm.

They argue that the management is failing to face up to the company's challenges.

"In life and in business, there are two cardinal sins," Mr Icahn wrote, in the latest instalment of a fight he began in August.

Carl Icahn has a record as a corporate raider

"The first is to act precipitously without thought, and the second is to not act at all."

He charges that Time Warner's management did the first by merging with AOL in 2000, just before the dot-com bubble burst, and by selling Warner Music and Comedy Central at a discount.

Meanwhile, a plan to buy back $5bn worth of shares and sell 16% of the group's cable TV arm reflected the "paralysis of inaction", he added.

Instead, the group should float Time Warner Cable altogether and buy back $20bn in shares.

Mr Icahn has also promised to hire a consultant to analyse what he calls Time Warner's "bloated" costs.

AOL reforms

But Time Warner said it was sticking to its guns.

"The management team has proven its commitment to shareholders and its openness to constructive ideas from knowledgeable people," the firm said in a statement.

It said it would stick with plans to reform AOL, focusing on advertising returns, rather than dial-up subscriber services where it makes a loss.

"We will proceed on our course, committed to increasing the value of this company and delivering a highly competitive return for all of its shareholders," the firm said.