FOR A while, French drug barons seemed to have found the perfect way to deal in hashish and cocaine. Customers would dial up a message service on Minitel, the interactive teletext service run by the country's state telephone service, to place their orders. The dealers would then use France Telecom's Alphapage system to bleep their subordinates with details of the type and quantity of drug needed, and the destination.

It was only when the police closed in that the drug syndicate realised it had made no attempt to code messages. The dealers are now in prison awaiting trial.

Apart from demonstrating that criminals can be as touchingly naive about technology as the rest of us, the story is a reminder of an uncomfortable fact: that while pundits across Europe, Japan and America are debating the merits of information superhighways, one country - France - has already built a highway of sorts. Minitel has been in operation for 13 years.

When the service was launched as a pilot in 1981, it was marketed as a substitute for the telephone book - and small terminals consisting of screens and keyboards were distributed free of charge. Although customers now have to pay - the cheapest model rents for 27 francs ( pounds 3) a month -6,485,000 terminals are currently in use all over France. Half a million other users have equipped their personal computers with Minitel software and modems that allow them to tap into the state network.

Minitel has become notorious for its messageries roses, dating services where would-be partners can type out salacious conversations that often leave nothing to the imagination before fixing a rendezvous. But message services as a whole provide just 2 per cent of Minitel's business.

The most-used option remains the telephone directory, representing 33 per cent of the 89 million hours of connections per year. Next, with 18 per cent, is the professional use by companies that have opted for Minitel for their in-house communications rather than a conventional private computer system.

After that, 15 per cent of customers use Minitel to keep abreast of their bank accounts. Depending on the bank, subscribers can ask for a statement of their account or even carry out operations, moving money from one account to another at any time of day or night. Perhaps because of Minitel competition, it was only last month that France's first 24- hour telephone banking system was introduced.

Other services include rail and air reservations and advertising services - the customer seeking a second- hand Mercedes convertible only has to dial 3615 and tap in the code 'Mercedes' for a full list of all the models available through the manufacturer's French dealers.

By dialling 3617, then tapping in 'fax', a subscriber can type out a text and send it to any fax in the world. This dispenses with the need for a fax machine for the occasional user.

Although the system has made a large proportion of the French population comfortable with computer keyboards, it is held back by its slow transmission speed of 1,200 bits per second. A fourth generation of machines, dubbed TVR, for Teletel Vitesse Rapide (Fast-Speed Teletel), will run eight times faster, at a more respectable 9,600 bps. The first TVR programs for PCs will go on sale this month; terminals distributed by France Telecom will not reach the customer for another year.

Speed apart, the TVR's key strength is that it will represent Minitel's first faltering steps into multimedia. It will capable of transmitting high-quality colour images, a boon for hoteliers and estate agents, who will be able to accompany their advertisements with impressive photographs illustrating the range of merchandise on offer.

Even this upgrading, according to the daily Liberation, means that, 'on the famous information highways, Minitel will be in the slow lane . . .

ridiculously slow compared with the networks to which work stations and microcomputers are connected. But a small advance for a big public may perhaps be better than a big advance for a small public.'