Britain is facing a drug problem of potentially disastrous proportions, and more and more doctors here are doubtful that the longstanding policy of methadone maintenance treatment is the solution.

"Contrary to international myth, there is no magic system that has solved Britain's drug problem," said one government official. "We haven't yet faced up to the seriousness of heroin addiction here, let alone found answers."

Seizures of smuggled drugs have been increasing steadily, and last year they reached a record value of more than 52 million pounds.

The number of heroin addicts registered with the British Home Office increased by 17 percent in 1980 to 2,800. "These are just the ones we know about," said the official. "Multiply that figure by four and you get nearer to reality."

Heroin in Britain is currently coming from Southwest Asia -- the border area between Pakistan and Afghanistan -- and, despite the Islamic revolution, from Iran.

Over the last four years, street prices for heroin have remained stable at between 70 and 80 pounds a gram while the quality has improved steadily. Heroin is readily available on city streets, undiluted -- and thus easily liable to cause an overdose.

"This is not the same situation as the 1960s," the government official said. "Then people took acid and cannabis but not heroin. Now the taboos are off and heroin has become a 'recreational drug.' It's as easy to obtain at parties as cannabis used to be."

Those who used to smoke pot are now "snorting" heroin, that is, inhaling it through the nostrils. There also is a new, gray area: an increasing number of people not yet addicted to heroin, but who are using it socially once or twice a week.

Doctors in the overworked and underfunded National Health Service drug clinics say they are seeing more addicts from middle-class or wealthy backgrounds, many of whom snort or smoke heroin rather than inject it.

But despite the evidence that drug abuse in Britain is steadily growing, the problem is not yet a government priority.

There is no concentrated political interest, no national policy on drugs and the last parliamentary debate on the issue was in 1979. Unlike the United States, Britain does not have much crime that can be clearly blamed on drug addicts, so the problem has not really hit the man in the street. "There are no votes in drug addiction in this country," a British member of Parliament explained recently in a private talk to drug experts.

Drug abuse comes under the control of two different government departments, the Ministry of Health and the Home Office. There is no single minister responsible for the problem. There is also no central office for financing treatment clinics or rehabilitation centers, which are administered by local health authorities.

The Health Ministry says local people "know the grass-roots problem," but many narcotics experts insist that a national problem calls for a national answer.

A group of doctors and social workers signed a letter to The Times of London last October calling for a radical change in government policy before heroin abuse got out of control. There was no response.

In the London area, there are 14 treatment clinics for drug addicts and all are splitting at the seams. Most have waiting lists of six weeks or more and are finding it difficult to get adequate funding.

One of them is run by Dr. Pamela Aylett, a psychiatrist who works in a gloomy basement in Westminster.

She has 100 heroin addicts on her books but only one social worker, who works for half a day a week.

"We need one full-time social worker for every 20 people," she said. "But even if we could afford one, where would we put her? In there?" She gestured to a tiny kitchenette behind her office. "We need more staff, better premises, more room."

It is not only a shortage of cash that is worrying British drug clinics. For the first time, there is serious questioning of the method the majority of British clinics use in treating heroin addicts -- methadone maintainance therapy.

The cornerstone of British policy toward drug addicts has always been that the addict is a patient in need of treatment rather than a criminal to be punished.

Before 1968, any doctor could legally prescibe heroin to enable an addict to function in society.

In the mid-1960s, when heroin was attracting a new, younger group and when the number of known addicts increased rapidly, a licensing system was introduced giving only a limited number of doctors the right to prescribe heroin for addicts; almost all of them worked out of the newly established clinics.

Soon, the clinics began using oral methadone as a way to prepare their patients for eventual withdrawal. Heroin is now prescribed only invery rare cases of hardened addiction.

Methadone maintenance has always been controversial in Britain. Many users say that methadone is more addictive than heroin and that it is not as easy to wean an addict off methadone as originally hoped. Most methadone addicts have to go through the same detoxification as for heroin.

The real problem for the clinics is that patients on methadone will often remain on it for years -- and what was intended as a stabilizing substitute can become a lifetime support.

"Out of my 100 patients this year, only about 10 will come off methadone, some will disappear and the rest we will carry over," said Aylett.

"A methadone dose lasts 24 hours, longer than heroin does," she added, "but it has no other pharmacological advantages. Methadone is not the best treatment we will ever have. It's a stopgap. We still have no medicine that will stop the craving."

Methadone has now joined heroin in street sales here. Although doctors must be licensed to prescribe heroin, there are no restrictions on prescribing methadone, and officials say some general practitioners grossly overprescribe the drug because they know so little about it.

Patients then sell what they do not need on the black market.

As more doubts are being cast on the validity of methadone, doctors are also faced with a growing trend among the under-20s to use "poly-drugs" -- usually a mixture of barbiturates and alcohol, with heroin occasionally added.

The users are mostly between 16 and 20, drifters who hang out in London's Piccadilly Circus.

The only answer at hand for the disordered and chaotic lives of these addicts seems to lie in small, flexible rehabilitation and after-care centers.

One, Elizabeth House in the Earls Court district of London, is a successful family-type hostel for ex-addicts between the ages of 24 and 34. It will shortly open another house, concentrating on younger ex-addicts who are "polydrug" users.

Elizabeth House is big and shabby and has few rules but lots of space. An addict who asks to join must undergo detoxification. Residents have individual rooms. There are three full-time staff members and five part-time staff, who hold outside jobs but live at the house.

"Everyone is very free," said counselor Perry Newburn, himself a former heroin addict. "The idea is to be a supportive community."

Newburn has been off heroin for five years. He refused methadone as yet another addictive drug.

"What we try to do here is bridge the gap between the newly cured addict and society," he said. "People takes turns in cooking, do their own chores and help with maintenance around the house.

"But apart from that they are free to live as they want here. The only rules are no drugs, no violence and you must pay your rent."