Channel 4 on Tuesday blamed a worsening advertising market as it announced the sacking of 15 per cent of its workforce and swingeing cuts to less commercially attractive programmes.

The broadcaster, which said it would need a subsidy of up to £150m a year by 2012 to maintain its role as a public service broadcaster, said 150 jobs would go as part of £50m-a-year cost savings for 2008 and 2009.