ITV gave warning this morning that its advertising revenues would tumble by 9 per cent in the crucial Christmas quarter, reflecting the impact of a weak economy on the broadcaster of Coronation Street.

The commercial network also said that Jeff Henry, the executive ultimately responsible for ITV's controversial phone-in quiz show ITV Play, would leave the broadcaster. ITV's phone-in and online business will now be integrated into its channel operations.

John Cresswell, chief operating officer of ITV, said that the company was holding its share of advertising revenue relative to Channel 4 and its rivals for the first time in 25 years but admitted "we are trading in a tough market".

ITV estimated that the total television market would be down 9.4 per cent in the fourth quarter, reflecting a continuation of the poor performance seen since September.

However, the weak Christmas forecast was less than some analysts had forecast, with some expecting falls of as much as 12.5 per cent. ITV said that advertising revenues were in line with its previous predictions of a fall of between 4.5 per cent and 5.5 per cent in the second half of the year.

But Mr Cresswell also cautioned that ITV "was seeing a bit of weakness in the online market" for advertising, reflecting the fact that the downturn had spread to new media. The company's websites — ITV.com and Friends Reunited — will now report to Peter Fincham, the director of television.

Mr Cresswell said that trading would continue to be tough in 2009, but he could not give any exact predictions. However, he noted that analysts had forecast that television advertising would fall by between 5 and 6 per cent in 2009.

The forecasts were contained in a trading statement, in which ITV said that revenues for the first nine months of the year were £1.47 billion, down 0.9 per cent on last year.

Broadcasting revenues from its channels fell 5 per cent to £1.2 billion, while turnover from its production business, which makes shows for other broadcasters, was 35 per cent ahead at £206 million. Online revenues were up 6 per cent at £25 million, while ITV.com monthly unique visitors rose 23 per cent to 5.9 million.