British commercial broadcaster ITV said it remained cautious for the full year after hitting tougher comparatives in the second quarter due to last year's soccer world cup.

ITV, home to the X Factor and Coronation Street, said net advertising revenues were up 6 per cent in April, below some forecasts in the market, and said they would be down in May and June, without giving a precise figure.

Analysts had expected April trading to be strong as retailers spent on advertising around the royal wedding. Forecasts in the market for the month ranged from 8-12 per cent growth, following a 12 per cent rise in the first three months.

The fluctuating performance meant the group should post a rise in ad revenues in the first half of the year of 1-2 per cent, it said.

"As we anticipated, tough ITV1 world cup comparators in June mean we may slightly underperform the market in the first half," chief executive Adam Crozier said.

"While we expect to outperform the market across the whole of the year, we remain cautious about the economic outlook."

The results had been highly anticipated by investors after shares in the group underperformed the FTSE 100 Index by almost 5 per cent since April, on fears the recovery in ad markets would fall away in the second quarter.

Reuters