Rail unions have launched legal action to challenge coalition plans to reprivatise the East Coast service and to hand out direct awards of other rail franchises to private firms.

The three major unions – Aslef, RMT and TSSA – are seeking a judicial review of the government's decision to push through a rapid franchise competition for East Coast, currently operated by a state-owned company. East Coast was rushed to the top of a new timetable drawn up in the wake of the West Coast fiasco, which saw the Department for Transport's franchising programme left in chaos after the award was overturned and an investigation found serious flaws in the process.

Unions argue that the East Coast bidding competition – the only one to be run from scratch in this parliament – is being rushed through despite the recommendations of the Brown review of rail franchising that procurement should take at least 24 months. The unions say jobs and employment conditions, as well passengers' and taxpayers' interests, are put at risk, accusing the government of breaching its own commitment to conduct proper consultations.

The London-York-Edinburgh intercity service is run by Directly Operated Railways, which returns all profits to the state and has paid more than £600m in premiums to the treasury since taking over in 2009, when National Express walked away from its franchise contract. Before that, another private operator, GNER, was also forced to hand back the keys after admitting it could not meet the promised payments.

ASLEF general secretary Mick Whelan said it was imperative to raise the genuine concerns of all stakeholders and especially the employees. "We cannot, in good conscience, allow the mistakes of the past to happen again."

Unions compared the move with the recent privatisation of the Royal Mail – a debacle which the National Audit Office last week said cost taxpayers £750m in a single day.

The RMT's acting general secretary Mick Cash said: "It is shocking that they are engaging in the same tactics to try and hand the East Coast mainline back to their friends in big business."

TSSA leader Manuel Cortes added: "Rail workers are at a loss to understand why the government insists on going forward with a broken system which threatens the interests of passengers and taxpayers. We can only conclude that the ideology which saw Royal Mail flogged off on the cheap continues to thrive."

The second part of the legal challenge concerns the government's decision to make a direct award to First Capital Connect of an extended franchise agreement for the Thameslink franchise, without any tendering process. This is one of a series of direct awards, initially viewed as a stopgap while the DfT restored its franchising programme. However, operators such as Virgin Trains have already been granted new contracts, without competition, and the DfT could potentially grant First Group rights to run the Great Western service until 2020.

A Department for Transport spokesman said: "We will vigorously defend this claim and remain committed to the franchising programme. As these legal proceedings are ongoing it would not be appropriate to comment further at this stage."

Virgin Rail, First Group, and a joint venture of SNCF subsidiaries Keolis and Eurostar are the three shortlisted contenders for East Coast. Unless the judicial review delays the award, a new private operator is expected to be in place by February 2015.

Labour had indicated that it would leave East Coast in state hands if it won the next election in May 2015. Leader Ed Miliband last week said that his party would be looking for "innovative solutions" in its manifesto to reform the railways. While this would stop short of widespread renationalisation, one option being considered by Labour is allowing the state-owned Directly Operated Railways to compete to run franchises.