Traditional High Street chemists warn they could be forced out of business because supermarket chains have been given the go-ahead to launch rival services.

The Department of Health is relaxing restrictions which control the number of pharmacies in an area.

It means supermarket chains can open 24-hour outlets in out-of-town stores which can deal with NHS prescriptions.

Only stores which promise to open for more than 100 hours a week will be able to take advantage of the changes.

But pharmacists in Sussex say this could open the floodgates to a free-for-all.

Martin England, who is based at Ashton's Chemist in Brighton, said: "Any expansion of services is bound to affect the local community pharmacy.

"Now this chance has become available I am concerned it may open the floodgates to more and more places opening which could cause problems.

"If this is going to happen then there must be a measure of extra support for smaller pharmacies otherwise there is a strong likelihood of their demise."

Mahesh Shah is managing director of Nucare, a pharmaceutical company which provides business support and marketing and professional services to independent pharmacists across Sussex.

He said: "We believe the proposals will have irreversible consequences on local community pharmacies and that consumers and patients, especially the most vulnerable in our society, will suffer from reduced levels of care, service, choice and competition.

"The majority of patients who visit the pharmacy are over 50 and are not necessarily mobile. They are happy with the current distribution of pharmacies."

Smaller chemists say they will only be able to survive by opening close to a GP surgery to catch passing trade but those in more remote areas will struggle.

Pharmacists warn town centres will end up with clusters of chemists near surgeries and none in isolated areas.

Sainsbury's, Tesco and Asda have been calling for changes in the law for years and have welcomed the plans, saying they will create more choice.

John Evans, Asda's superintendent pharmacist, said: "This is a good and encouraging start that marks the beginning of the end for the pharmacy 'closed shop'.

"Customers will be pleased at the news - it is their number one demand for a service we should provide."

The Department of Health says the changes will put the needs of patients first and the increase in competition will drive down the cost of over-the-counter drugs.

Thousands of people in Sussex supported a campaign launched last year when the Office of Fair Trading first suggested scrapping all controls over the number of pharmacies opened up.

Independent pharmacies across the county, including HA Baker in Lewes and Watts and Co in Brighton, called for the help of customers and MPs to back the campaign.