Jonathan Dimbleby has called Royal Television Society (RTS) executives cowards for scrapping an award for journalists in Gaza because they did not want to deepen the controversy around a BBC documentary on the conflict.

The historian and presenter is one of 300 TV and film professionals who have signed a letter to the society criticising its last-minute decision not to award the prize at an awards ceremony last week, as a result of the fallout from Gaza: How to Survive a Warzone.

The documentary was pulled from BBC’s online streaming services in February and is the subject of an internal investigation after claims emerged that Abdullah al-Yazouri, the film’s 13-year-old narrator, was the son of Hamas’s deputy minister of agriculture.