THE Government unveiled a national network of vehicle-testing centres in a crackdown on air pollution yesterday - but forgot to tell all the cities involved.

Transport Minister Gavin Strang announced that, starting in July, free emission testing and advice on vehicle maintenance will be available in eight pilot areas: Westminster, Bristol, Birmingham, Canterbury, Middlesbrough, Swansea, Glasgow and Belfast.

The move is designed to complement random roadside emission testing which has been running as a pilot project in the eight cities. Local authorities have had the power to hand out #60 on-the-spot fines to motorists whose cars failed the tests.

However, the news that free testing centres are to be created within the next two months took the man responsible for running Glasgow's operation by surprise.

Mr Brian Kelly, the city council's director of environmental health, said he could not comment on them as he knew nothing about it.

''There are some serious issues here,'' he said. ''Where are we going to put these centres for a start? Who is going to staff them? Where is the equipment and training coming from?''

Glasgow has been heavily involved in random roadside checking, but like many other authorities involved in the project, no fines have yet been handed out to motorists. Legal complications with the fixed penalty forms have delayed their introduction, although they are expected to get off the ground later this year.

The free tests are intended to complement the trial powers granted to those local authorities to fine motorists with dirty exhausts as part of the Government's ''greener vehicles'' campaign. If the pilot scheme works, it will be brought in nationwide.

Dr Strang yesterday encouraged people to buy and run environmentally-friendly cars as well as maintain existing vehicles properly. ''Just two weeks ago we had to issue the first smog warnings of the summer,'' he added. ''Let's all do our bit to walk, cycle or use public transport a little more. And when we're using the car, make sure the engine is tuned because we all have a part to play in the war on smog.''

Preliminary results from the pilot areas have revealed that nearly a fifth of all vehicles exceed emission limits, with diesel cars, vans and taxis among the worst offenders. Provisional recommendations made by a working group monitoring the trial results already include providing cheap self-service emissions tests at petrol stations.

The AA welcomed the introduction of emission testing for motorists but said it would not improve a system which had already proved ineffective. The scheme was ''fundamentally flawed and is driven by the need to collect lots of income from fines to pay for the enforcement,''said spokesman John Dawson.

''That means a fair amount of short cuts in the process, with lots of people fined, even though they have sensible mitigation.

''For example, they may not have known there was something wrong with their car and they have just had it serviced. There is also no need for anyone who is caught to put the fault right, as there is with other vehicle defect schemes,'' he said.

Dr Strang said that most people accepted that pollution was at levels that posed a health hazard in some cities. ''It's a threat to people with asthma and also to people who have a heart condition, so we are determined to clean up these city areas,'' he said. ''That means effectively enforcing lower emissions from our vehicles.''

He said the introduction of pilot testing areas was a step forward, but the Government was not pretending it could change the world overnight. Encouraging people to ''green'' their cars by keeping them tuned was quite a separate issue from encouraging people to use cars less.

''No-one is suggesting that vehicles testing is going to deal with the need to use our cars less, and that means we have got to provide better, more reliable public transport, to encourage people to walk or to cycle,'' he said.