LONDON - Britain's intelligence chiefs will give their first ever public testimony on Thursday when they are cross-examined together in parliament about the case of former US spy agency contractor Edward Snowden.
The evidence-gathering session comes amid calls for the government to step up oversight of its three main intelligence agencies after documents that Snowden leaked to the press exposed Britain's role in secret mass surveillance programmes.
Those disclosures detailed Britain's close cooperation with the US National Security Agency (NSA), embarrassing Prime Minister David Cameron and angering lawmakers in his ruling Conservative party who said they harmed national security.
The director of Britain's electronic eavesdropping agency GCHQ, the head of the domestic security service MI5, and the chief of the foreign Secret Intelligence Service, otherwise known as MI6, will all attend Thursday's hearing, which will be televised, albeit with a short delay for security reasons.
In the past, such hearings have been behind closed doors.
"(The intelligence chiefs) have traditionally operated behind a veil," a government spokesman said. "But they are more publicly available than they have been in many years. This is a step forward in terms of transparency."
People familiar with the agenda said the officials would be asked whether mass surveillance programmes were a violation of privacy, and what impact the Snowden leaks had had on their work.