The BBC's Panorama investigation into TV phone-in scandals attracted a significant audience last night.

Around 4.1million viewers - a 16.9% audience share - tuned into see the report on GMTV's premium rate competitions. The programme alleged the broadcaster's phone provider Opera had chosen winners before competition lines had closed, meaning viewers were calling in with no chance of winning.

Following yesterday's media coverage, GMTV has cancelled Opera's contract with the programme, and its managing director has Paul Corley has apologised to viewers.

The BBC show peaked at 4.5 million at the end of the programme, making it the highest rating in this series of Panorama. The last highest was 4.01 million on February 5, for a documentary about have-a-go heroes called "Should I Fight Back."