Unions are to demand new rights to strike as the price for keeping the cash-strapped Labour Party afloat.

Repealing the ban on secondary industrial action is among a swath of left-wing policies that unions want to see in the Labour manifesto. The pressure on Gordon Brown comes as he is relying on the unions to help to avert Labour’s cash crisis, when they are in increasingly militant mood.

Refuse collectors, librarians, teaching assistants and dinner ladies announced yesterday that they would strike for two days on July 16 and 17 after rejecting a 2.45 per cent pay offer, potentially closing thousands of schools in the last week of term.

Unison negotiators, announcing the dates, said that up to 600,000 of their members in England, Wales and Northern Ireland would walk out in the first of a series of “sustained strikes” by council workers.

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As unions begin to flex their muscles on the ground, they are working to maximise their leverage over the Prime Minister at a time when the Government is politically vulnerable and the party is financially parlous.

Over the past few months large donations to Labour of the type enjoyed by Tony Blair have all but dried up, leaving the party increasingly reliant on its traditional paymasters. In the first quarter of this year, union contributions made up 88 per cent of the party’s income, up from 51 per cent in the same period last year, according to the Electoral Commission.

The party has until the end of the month for auditors to sign off its accounts and submit them to the Electoral Commission. Any delay would be hugely embarrassing since it could suggest the governing party is not solvent, and the party is still negotiating with private donors to ensure it remains afloat.

Five weeks before Labour chiefs meet to decide the outline for the next general election manifesto, Unite, which gave £2 million earlier this year to the party to help campaigning projects, is preparing to launch a concerted campaign to overturn the ban on secondary action by workers employed by the same company, which was introduced by Margaret Thatcher. Labour promised to repeal the measure after it was introduced in the 1980s, but dropped the commitment before the 1997 election.

Other possible changes to union law were a provision enabling unions to ballot their members by phone or e-mail. Business groups expressed fury when they discovered that in the final months of Tony Blair’s administration the Government was examining the case for “non-postal” ballots.

The Labour leadership will face demands from the GMB union for the upper earnings limit on national insurance to be abolished, which it hopes will redistribute tax. National insurance is charged at 11 per cent on an employee’s income between £5,460 a year and £40,040 a year, and 1 per cent above that.

The union is also intending to press the Government to look at the way the oil market operates, in the belief that oil companies are exploiting London’s light-touch regulation in a way that harms members.

Other demands likely to be made by the unions, according to Tribunemagazine, include: mandatory company audits to ensure equal pay between men and women, a policy supported by Harriet Harman before she became deputy leader; new rules to protect the jobs of workers whose companies are bought out by private equity firms; reform of the minimum wage, with some unions keen to see the end of age-based banding; a greater commitment to producing more goods and services within Britain, without breaking EU law.

Although the Prime Minister will be reluctant to be seen to bow to the demands of the unions, privately they say he has been far more willing to listen to their demands than Tony Blair.

Labour sources said they would strongly resist union demands to change the rules on secondary action. The issue will come to a head at the end of next month, when the party has its three-yearly National Policy Forum, likely to be held in Warwick.

Last night businesses representatives said that unions must not be able to buy Labour policy. John Cridland, deputy director-general of the CBI, said: “The unions seem to think it’s OK because they are putting money into the war chest to form policy. We don’t.”

Trouble ahead

Unison, July 16 and 17

600,000 local government workers, including teaching assistants, refuse collectors, librarians, catering staff and lollipop ladies. They rejected a pay offer of 2.45 per cent

Public and Commercial Services Union, autumn

Possible strike ballot and industrial action involving up to 300,000 civil servants. Any action would affect Whitehall departments, benefit offices, Revenue & Customs, driving tests and museums. The union is opposed to the 2 per cent limit on public sector pay

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