By Richard Black BBC science correspondent

This year the National Institute of Allergy and Infectious Diseases (NIAID) will divert $145m to buying the experimental vaccine and testing it.

Research is being conducted into finding more affordable medication

Half will come from the NIAID's own bio-defence budget, a quarter from its HIV projects, and the remaining quarter from research on other diseases. A further $131m will come from NIAID's budget for the fiscal year 2004.

A number of Aids researchers say their work is already being affected by the cuts; and campaigners say this could be the start of a trend whereby funds for medical research are diverted to bio-defence.

New vaccine

In his budget for 2003, President George W Bush asked Congress to provide funds for purchasing and evaluating a new anthrax vaccine.

Congress declined, but the White House has now instructed NIAID to find the funds by cutting back on other projects.

An anthrax vaccine already exists, but it cannot be given safely to the old, the young and the immuno-compromised.

The president talks the talk on Aids internationally, but if you look at his record domestically, the administration is extremely hostile to HIV/Aids programmes Gregg Gonsalves, Director of Treatment and Advocacy at GMHC

The administration wants to have a second-generation vaccine which will be safe for everyone.

Dr Luis Montaner from the Wistar Institute in Philadelphia has just started an HIV research project which has had its funding cut.

"This basically means for our own research that we have to scale back, to re-address our aims and perhaps accomplish less than what we would have hoped we could accomplish," he told the BBC.

"If there is a commitment that bio-terrorism needs to be met by a comprehensive scientific agenda which includes, for example, anthrax vaccines, that should not be at the expense of other, equally important research programmes."

Support for Africa

Dr Montaner's team is evaluating a potentially cheaper way of using anti-retroviral drugs in southern Africa, one of the regions Mr Bush has been visiting on his current African trip.

"This is happening at a time when the administration and Congress are putting a special emphasis on Aids," observed Robert Guidos, director of policy and government relations at the Infectious Diseases Society of America, the professional organisation for researchers and doctors in the field.

Since 11 September terrorism has been top of the agenda

"The Bush administration and the department of state have said that Aids is a national security issue; that we definitely want to do more in Africa", he said. "Here we have an opportunity to do more, and yet we're taking away the research dollars."

A number of scientists, campaigners and members of Congress - including Senators Arlen Specter and Tom Harkin - have written letters of protest to the White House, some calling the move a "misuse" of research funds.

If the money needs to be found, they say, it should come from the Homeland Security budget.

Gregg Gonsalves, Director of Treatment and Advocacy at Gay Men's Health Crisis in New York, told the BBC that bio-terrorism is distorting research priorities.

"It's unprecedented for an administration to raid the biomedical research programme," he said. "The president talks the talk on Aids internationally, but if you look at his record domestically, the administration is extremely hostile to HIV/Aids programmes."

Ever since the events of 11 September 2001, there have been warnings that bio-terrorism would at some point start taking research funds away from other diseases.

This, according to campaigners in the US, is the first concrete sign of it happening in practice.