An independent panel has criticised America's space agency (Nasa) for overspending and described its running of the International Space Station as "not credible".

The panel, including two Nobel laureates, spent three months looking into the agency's finances.

It concluded that the agency could not move forward "without radical reform" and recommended cuts in the space station's workforce and shuttle missions.

The report detailed the severe spending problems Nasa has faced since the ISS, a $95bn joint project with Russia and agencies from Europe, Japan and Canada, began construction.

These included:

• A projected $4bn to $5bn in space station cost overruns over the next five years;
• An increase in the estimated cost of the ISS from $17.4bn in 1993 to roughly $30bn, due to launch delays and unreasonable budget caps set by Washington;
• The requirement of $8.3bn from Washington to finish the job over the next five years.

The panel was uncompromising in its criticism of what it said were serious flaws in the agency's management.

"The existing deficiencies in management structure, institutional culture, cost estimating and program control must be acknowledged and corrected for the program to move forward in a credible fashion," it said.

Cost cutting

To combat the cost overruns, the panel recommended a strict regime of cost cutting, including:

• A reduction in the space station's work force;
• A reduction in the number of shuttle flights to the space station from the current six to four a year to save $668m from 2002 to 2006;
• Changes in space station management, so one person oversees both the construction of the project and the scientific research on board.

The report was unveiled on the first anniversary of permanent occupancy of the space station.

It was commissioned in July this year by outgoing Nasa Administrator Dan Goldin - the same month members of the US Congress mounted a concerted bid to restrict the space station's funding.

The panel task force is to present its findings to the Nasa Advisory Council on Tuesday. The House Science Committee will discuss the report on Wednesday.

Science Committee chairman Sherwood Boehlert said that the committee would be monitoring Nasa's progress over the next two years.

"We will be overseeing Nasa closely to ensure that those changes are made," it said.