Labour is funding trade union activity inside Whitehall with millions of pounds of taxpayers’ money, The Times has learnt.

Government departments are paying the salaries of dozens of union officials, some earning more than £60,000 a year, who do no work for the taxpayer.

The Conservatives expressed horror last night at the “cadre of union officials” embedded across Whitehall.

Ten departments have revealed that they employ 46 full-time and 87 part-time officials to work exclusively for the unions at taxpayers’ expense. Their salaries cost between £150,000 and £4.5 million per department. They are also given access to office space, computers and photocopiers worth an estimated £1.2 million each year.

A Whitehall whistleblower has told The Times that union officials spent time on “far-left political campaigns and making up false claims about the Conservative Party”. Civil servants are bound by impartiality rules.

The whistleblower also claimed that union officials are given promotions worth thousands of pounds, despite working outside their departments’ remits. The source added: “This is a two-tier system where ordinary civil servants work for a living and strive for years to get promotion, while political cliques in unions get their chums into taxpayer-funded jobs where there is no job.”

One senior official with the Public and Commercial Services Union (PCS), Karen Abram, lives in Lancashire but has her travel and hotel bills paid by the Department of Health so that she can work in London. The department said that Ms Abram was a “home worker” and that her expenses complied with internal guidelines.

The disclosure, which comes the day before Gordon Brown addresses the TUC conference, has revived accusations that Labour has done favours for its union paymasters.

Several departments, including the Treasury, did not respond to requests for information, which means that the total value of assistance could reach £10 million a year.

According to Electoral Commission records, union donations accounted for £5.4 million, or 69 per cent, of Labour’s fundraising in the first six months of the year.

The scale of the union assistance has caused surprise. One union source said that in an ideal world, there would be one full-time official for every 2,000 workers. However, the Home Office has 83 full and part-time union officials for its 70,000 employees: one for less than every 1,000.

Francis Maude, the Shadow Cabinet Office Minister, said: “On top of office costs, it is now clear that the Government is bankrolling a cadre of full-time union officials across Government, costing millions of pounds a year. There needs to be full openness and transparency on these costs so taxpayers can know whether this is appropriate public expenditure and represents value for money.”

A spokeswoman for the Cabinet Office said: “Since 1996, departments and agencies have been able to set their own levels of trade union facilities time, but we do not collect this information centrally. Like many employers, civil service departments follow the Acas code of practice — time off for trade union duties and activities — when agreeing facilities with their trade unions.”

Senior union officials, including Paul Kenny, the general secretary of the GMB union, have regarded attempts by Mr Maude to uncover information about trade unions’ work in Whitehall, as a declaration of war. He told The Times that unions were more heavily regulated than the banks.

The three unions that work inside Whitehall are the PCS, Prospect and the FDA (First Division Association).

Trade union representatives are in theory banned from interfering in the formulation of policy, although some officials suspect that this may take place informally. This was denied by a spokesman for the PCS. “Typically these individuals take up personnel complaints and negotiations with management. In some departments, this is negotiating and some take people on full-time,” he said.

Times Recommends

• Times Christmas appeal: Letter from the Editor
• Conferences — what a waste of money
• Schools supremo learns a painful lesson