The row over the siting of Britain's Pounds 200 million X-ray source for researchers deepened this week with unions at Daresbury saying they "strongly suspect" the Wellcome Trust of vetoing the original choice of their Warrington-based laboratory.
The choice is between Daresbury, where the current X-ray source was established 20 years ago, and the Rutherford Appleton Laboratory in Oxford.
Until early this year the policy of the Central Laboratory for the Research Councils, which runs both laboratories, was for the source to be located at the Daresbury site.
The government is expected to announce its decision in the next few weeks. Unions have warned that Daresbury will close down if the source goes to Rutherford.
The unions are accusing the charity Wellcome of "throwing its weight around" on the back of its Pounds 110 million grant to the project and Pounds 300 million towards the joint infrastructure fund for university laboratories.
They believe the trust has an "unhealthy level of political influence" as a result of its donations and suspect it of pushing for the source to be located within the "Oxford-Cambridge-London golden triangle".
The trust has consistently maintained that it is for the government to decide the location of the source and will comment only after its decision.
A spokeswoman said: "The trust has put forward its scientific requirements and is now awaiting definitive proposals from government."
But unions at Daresbury said: "Science minister Lord Sainsbury and trade and industry secretary Stephen Byers have had to acknowledge the strength of Daresbury's case and freely admit that the views of the Wellcome Trust remain an important issue."
The unions were told recently by the government that the trust's Pounds 110 million will not be available towards the Pounds 200 million capital cost, as had been assumed, but will instead be for use over the course of the source's 15 to 20-year lifetime.
A union spokesman said: "The trust has moved the goalposts and this should reduce its influence proportionately. The whole affair and its role in it leads to big questions about how decisions are made in the wider public interest in an era of such public-private partnership."
The trust said its Pounds 110 million will be used for capital and recurrent costs and the exact details are still the subject of negotiations.