LONDON: Uncertainty prompted by the national debate over whether the UK should leave the European Union or not has caused ITV to lower its forecast for its first-half advertising revenues, the UK commercial broadcaster has announced.

ITV said in a trading statement that overall revenues grew 14% to £755m in Q1 2016 and that non-advertising revenue increased 34% to £428m.

However, advertising revenue in the first half of 2016 is expected to be broadly flat after a 13% decline in net advertising revenues in April, the Independent reported.

"This is against the backdrop of uncertainty in the UK advertising market, which we have experienced since the debate over Brexit began, and significantly higher share of our programme spend in the first six months," said Adam Crozier, ITV's chief executive.

ITV's announcement provides further evidence of the impact the referendum campaign is having on business investment decisions and comes as the pro- and anti-Brexit camps raise their efforts now that the national and local elections are over.

The debate is dominating the news agenda in the UK and now the advertising industry has entered the fray with the release of a poll showing the great majority (88%) of UK advertisers believe the country would be better off in the EU.

The Institute of Practitioners in Advertising (IPA) received a 33% response rate to a survey sent to all its members, including most of the UK's largest agencies.

Although some declined to take part because of the sensitivities surrounding the issue, the IPA reported that just 4% of respondents felt prospects would be better if the UK left the EU, while 8% thought it would have no impact either way.

"I believe this is an issue of vital importance to the industry we all work in and love. I also believe we should make our voice heard in the debate," said Tom Knox, president of the IPA.

"With advertising contributing over £100bn to the UK economy and responsible for employing over 150,000 people in the UK it's too important for our industry not to have a collective view of what's happening within society," he added.

Data sourced from ITV, Independent, IPA; additional content by Warc staff