The museum is a major draw for overseas visitors

Academics said inflation-proof government grants alone would not protect its long-term future.

The museum relies on a �38m government grant, and director Sir Neil Chalmers said there were "alarm bells" over its ability to compete with other venues.

Each year the museum attracts three million visitors.

NATURAL HISTORY MUSEUM Built in 1881 Employs more than 300 scientists More than three million people visit each year Adds �190m annually to the UK economy Last year's turnover was �52m UK's fifth most popular free visitor attraction

The museum commissioned the report - by experts from the London School of Economics and Imperial College - in order to draw attention to its "value to the nation".

It said the museum - which is free to enter - would not be able to compete adequately with private facilities that charged for entry.

"The resources of the (museum) will have to be able to increase at least in line with leisure expenditure in the wider market," it said.

Its annual government grant includes an extra amount to compensate for the introduction of free visitor entry in 2001.

Director Sir Neil said: "The nation should be proud of what the museum is achieving despite an ever-changing and increasingly competitive environment."