Current plans will create a "frighteningly complex hybrid" of Tube and rail networks with an inevitable undermining of safety across the proposed London Overground network, the RMT says. Activists have distributed campaign postcards to commuters at Whitechapel, Canada Water and New Cross stations.

"We asked London Underground and Network Rail exactly who would be responsible for operations and infrastructure on the East London Line and London Rail concession and the answers are simply frightening," general secretary Bob Crow said.

According to the RMT, TfL's plans mean at least eight organisations will be involved in running the new service. Of these eight, two will be responsible for signalling operations, two for infrastructure maintenance, two for infrastructure renewals, one for train and station operations and one for train maintenance.

It bases this on the following prediction of how operations would be managed on the new East London Railway, which is due to open by 2010.

* Track, station and signal maintenance and renewals between Dalston Junction and New Cross/New Cross Gate would be the responsibility of London Underground but sub-contracted to a private contractor.

* Track, station and signal maintenance between New Cross Gate and West Croydon and Crystal Palace, and from Dalston to Highbury and Islington and the rest of the North London Line would be responsibility of Network Rail. Renewals for the same section of line would be sub-contracted.

* Signalling operations between Dalston Junction and New Cross Gate would be the responsibility of London Underground, but between New Cross Gate to West Croydon and Crystal Palace, and from Dalston to Highbury and Islington signalling operations would be the responsibility of Network Rail.

*Through a franchise agreement with Transport for London a private train-operating company would have direct day-to-day responsibility for the operation of trains, stations and ticketing.

* Responsibility for building and maintaining trains would be the responsibility of Bombardier, although the trains will be owned by Transport for London.

*It is not yet clear who will have responsibility for the cleaning of trains and stations.

Crow added: "It seems that precious few lessons have been learned from the nightmare fragmentation of national rail privatisation or the disastrous part-privatisation of Tube infrastructure, because the same dangerous formula is being lined up for London Rail.

"It is not too late to step back from a grave mistake and keep the East London Line's operations as a unified part of the Tube network. We are urging commuters to join the campaign and tell TfL to keep the East London Line public," he said.

The existing East London Line is part of the London Underground network with signalling, train and station operations controlled by LU. Maintenance and renewals are sub-contracted to infraco Metronet.