Sky today announced it would record a £343m loss on its shares in ITV in its first-half results.

The accounting loss reflects the drop in value of its 17.9% stake which it bought for £940m in 2006.

The announcement comes ahead of Sky's half-year results report tomorrow. It coincides with but is not directly linked to the government's announcement that it must cut its ITV share to less than 7.5%.

To calculate the impairment loss Sky used the ITV share price on the last trading day of its fiscal half-year.

Analysts have noted that if it has to sell much of its stake at current market prices it will lose about £250m.