ITV programming chief David Liddiment is stepping down after five years with the channel following what he called an "extremely difficult decision".

His decision comes during a turbulent period for the network after the collapse of pay-TV system ITV Digital.

ITV saw the departure of chief executive Stuart Prebble in May and the retirement of network chairman Leslie Hill last month.

Mr Liddiment is likely to stay in post - as director of channels - until a successor is found towards the end of the year, a statement from ITV said.

Liddiment was an outspoken figure

The outgoing director said in the statement he had "loved this job more than any other in my career".

"To give it up has been an extremely difficult decision, but after five years I feel that it is time to hand over the reins and move on."

There is already speculation about his replacement, with Channel 5 boss Dawn Airey, Channel 4's director of programmes Tim Gardam and senior Granada executive Simon Shaps among the possible contenders.

Ms Airey has had success in establishing a niche for her channel, while Mr Gardam has overseen improved ratings.

Mr Liddiment's departure will come as a shock to many in the television industry - with pundits speculating he wanted to go out on a high - although shareholders are likely to have been informed earlier in the week

The former BBC head of entertainment was appointed director of programmes at ITV in September 1997, and became director of channels in April 2001.

His time with the channel has seen it score successes including Who Wants to be a Millionaire?, Popstars, and Pop Idol.

Peaktime defeat

But in May, the channel announced �28m of extra funding for programmes amid reports it was shelving dramas to save money.

It had found itself with a smaller peaktime audience share than BBC One for the first time ever in the same month.

The network has also been under pressure since the collapse of ITV Digital, the pay-TV network backed by major ITV franchise-holders Carlton and Granada.

He is without doubt one of the finest programme directors of his generation

Clive Jones ITV joint managing director

And ITV has had only mixed results in recent ratings wars with the BBC.

Scheduling football highlights during Saturday peaktime and trying to move the flagship ITN news bulletin were both seen as failures.

Poor ratings for the 7pm edition of The Premiership and criticism of the show's format saw Blind Date - which had originally held the spot - return.

Mr Liddiment added: "Despite the financial and competitive challenges we have faced most recently, there is a terrific spirit alive in ITV that I know will see it thrive in the future."

He said he would miss working with his team which he said was the best in UK television.

Managed departure

"I am also proud to have been associated with some of the most exciting, high quality and creative programmes of recent years and for that I thank the many producers, writers and performers who have contributed so much during my time at ITV."

Clive Jones, ITV's joint managing director, said: "I've known David for many years and he is without doubt one of the finest programme directors of his generation.

"It's a mark of his commitment to ITV that he is managing his departure so carefully and we thank him for that.

"His contribution to the channel and its programmes over a long ITV career has been immeasurable and he will be an extremely hard act to follow."

Mr Liddiment was instrumental in signing up a number of major stars on "golden handcuffs" deals such as EastEnders favourites Ross Kemp and Martin Kemp, as well as pulling off the coup of attracting Des Lynam after a long career at the BBC.