Channel 4 said Dispatches has discovered "a number of hard left revolutionaries inside and influencing Momentum, one of whom advocated a “flood” into the Labour Party and others that want to oust anti-Corbyn MPs and party officials".
The programme’s undercover reporter also heard how Momentum tried to conceal some of its activities and how campaign funds meant for Corbyn’s leadership campaign may have been misused, Channel 4 said.
Gavin Millar QC, who was interviewed for the programme, told Dispatches: “The Labour Party, following this broadcast, should investigate who in the Jeremy for Labour campaign was responsible for overseeing the arrangements for the payment of those staff and their presence in the Unite offices while they were doing Momentum work. Somebody is responsible.”
Momentum was set up following Corbyn's Labour leadership election last year to garner enthusiasm in the grass roots for the left-wing of the party. Earlier this year, Momentum called off a Corbyn support rally at the last minute, citing "overwhelming demand" as the reason for the cancellation.
Dispatches: The Battle for the Labour Party will air on Channel 4 tonight at 7.25pm.