About 4,500 BBC editorial staff have participated in a Safeguarding Trust workshop, it has been revealed.

Some 17,000 employees will complete the course, which is aimed at stopping programme staff from misleading viewers, by March.

Vin Ray, director of the corporation's college of journalism, said on Wednesday senior managers had already taken it and director-general Mark Thompson was pencilled in for Friday.

He said the workshops were led by BBC staff and would cost about £500,000 in total which would come from normal training budgets.

In the sessions, groups of 10-20 watch potentially unacceptable clips and debate them. They include a news interview using cutaway and noddy shots and the Gordon Brown Newsnight film that was edited in the wrong order.

The training department is also developing the workshop as an online course that may be used for staff at indies.

Controller of network production Anne Morrison insisted the workshops were not intended as "an honesty course".

She added: "We cannot teach people to be honest in two hours. If they are not honest we should not be employing them."