Investigating police claim they have evidence of a nationwide "bribery system" in which doctors allegedly prescribed 7-8% more Glaxo products each year in return for "freebies" such as Caribbean trips, stereo systems and wine.

In some cases, doctors received cash "gifts" ranging from £300 to £1,000, said the investigating prosecutor, Guido Papalia, in the northern town of Verona, where Glaxo has its Italian headquarters.

Glaxo played down the allegations. "We have a code of conduct and we try to follow it as scrupulously as possible," said Giuseppe Recchia, the spokesman for GlaxoSmithKline in Italy.

"Glaxo is a leader in the world pharmaceutical market. We do not need to do anything here that we do not do in other European countries," Dr Recchia said.

Dr Recchia said the company was awaiting further details of the allegations from the Italian authorities, after financial police searched 48 offices of its sales people throughout the country on February 7.

The police investigation is centred on communications between 30 doctors and 40 Glaxo salespeople between January 2001 and December 2002. Police say that emails, documents and tapped phone calls they have collected suggest more than 3,000 medical professionals may have been involved.

The investigators claim that €100m (£66m) declared by Glaxo in June 2001 as "investment to promote pharmaceuticals" was spent on free gifts - including luxury travel - for Italian doctors and other medical professionals.

But Dr Recchia argued that "travel" was not a crime, and health professionals had to attend international conferences to have the latest information on pharmaceutical developments.

Glaxo faced similar allegations in Germany last March, over allegedly offering perks such as free World Cup and formula one trips to thousands of German doctors between 1997 and 1999. The company, the biggest drugs firm in Europe, said at the time it would investigate the allegations internally and Europe-wide.

The company said at the time that many positions had been redefined and "responsibilities have changed" because of restructuring after Glaxo Wellcome merged with SmithKline Beecham in 2000.

Glaxo Wellcome was also investigated in 1995, during an Italian crackdown on corporate corruption, for allegedly bribing health ministry officials.