Labour has provoked a furious media row with accusations that TV broadcasters have incited and colluded with protesters on the ministerial election campaign trail.

A leaked letter sent to BBC, ITN and Sky from Margaret McDonagh, Labour's general secretary, alleges that broadcasters have crossed the line between making and breaking the news.

She claims that there is "growing evidence" that the broadcasters have been hand-picking individuals, pushing them into confrontations with leading Labour figures.

All three news organisations have denied the claims. The BBC said it had no evidence of any collusion.

The letter is primarily thought to refer to a visit by Tony Blair to Norfolk and Lincolnshire on Friday where outspoken critics were vocal in their opposition to the prime minister.

McDonagh claims that during the visit "there were protesters following the prime minister and they were given more information than they should have been".

"People's safety is at risk when these sort of things happen," McDonagh told broadcasting chiefs.

The row is an embarrassing one for Labour, provoking accusations of Millbank "control freakery" following a number of uncomfortable encounters between ministers and the general public.

Calling for a high level meeting with media bosses the Millbank supremo warned that broadcasters' behaviour "puts at risk the safety of Labour Party staff, politicians and the public".

The campaign has been dogged by poor relations between Labour and the TV media with a series of rows over access to Blair and revelations that both the BBC and ITN have considered making formal protests to the party.