Tubelines has voiced concerns that funding for the tube upgrade will be cut after it emerged that the government will have to spend £2bn to bail out rival consortium Metronet.

Last week Ruth Kelly, the transport secretary, admitted that the government would foot the bill because of guarantees that limited the liability of Metronet’s five owners, which include Balfour Beatty and Atkins. Metronet, which looks after most of the tube’s lines, went into administration last July.

A Tubelines spokesperson said: “We’re concerned it may have a financial knock-on effect when the strategic review happens in 2010 … the tube still needs funding.”

Tubelines runs the Northern, Piccadilly and Jubilee lines.

A Department for Transport spokesperson dismissed the fears, saying: “There are no grounds for that concern because there is vital work that still needs to be done. The government still intends that there will be private sector involvement.”

Balfour Beatty and Atkins declined to comment.

Meanwhile, the Amicus section of the Unite union has written to Transport for London to complain that companies that had won jobs in the wake of Metronet’s collapse were not members of the Electrical Contractors Association or the Joint Industry Board.

It said 1,000 electricians had been laid off when Metronet went into administration but had reason to believe work was being carried out secretly by other firms.

A union source said qualified electricians were keen to get back to work: “There's a lot of people out there prepared to deliver a good day's work, it's public money now so let's get on with it.”