The Commons Health Select Committee is to investigate the methods used by drug companies to pressure the NHS into prescribing their medicines.
Their action follows a decision by the Medicines Control Agency to take action against two companies, Schering Healthcare and Biogen Ltd, both of whom have set up and funded websites, newspaper advertisements and public relations campaigns.
The companies have been forced to withdraw campaigns calling for the drug beta-interferon to be made available to all MS sufferers. This follows complaints from the Multiple Sclerosis Society that the companies implied that patient groups campaigning for beta-interferon were acting independently. In fact, they were created by the companies.
Last night Schering admitted to the Independent on Sunday that no patients were involved in setting up or organising its so-called patient group. Biogen said patients were involved in their campaign but could not provide any names, claiming to do so would breach confidentiality.
But both companies insisted that they had done no wrong. They said the campaigns were designed to enable patients to take part in the debate about making the multiple sclerosis drug available across the NHS.
However, the Medicines Control Agency, the official body which regulates drug advertising, forced Biogen to withdraw its "Action for Access" campaign because it breached strict rules banning drug companies from advertising prescription medicine to the public.
A second patient group called MS Voice, funded and created by Schering Healthcare, has also been forced to withdraw advertisements in national newspapers by the MCA. Now the MCA is investigating the MS Voice website following complaints by the Multiple Sclerosis Society which insisted that patients had been deceived.
MS Society chief executive Peter Cardy said: "We have received a number of complaints from people who thought these were genuine patient groups."
Drugs companies spend nearly £50m a year in the UK promoting their products in the medical press. But as doctors are under increasing pressure to cut the £6bn-a-year NHS drugs bill, the Consumers' Association says this is forcing drug companies to look at ways of making the public aware of their products.
David Hinchliffe, the chairman of the Health Select Committee, said they would be questioning the Government's new drug licensing organisation, the National Institute for Clinical Excellence (Nice), about links between drug companies and patient groups.
Mr Hinchliffe said: "The tentacles of drug companies extend far and wide. There are some clear connections which do raise questions about the objectivity and independence of organisations concerned."