THE CHAIRMAN and chief executive of Scottish Nuclear yesterday admitted that ''failures in rigorous safety procedures'' at Hunterston B power station are behind a radiation scare surrounding some of the UK's best-known brands of food and drink.

Dr Robin Jeffrey also admitted that a potential link between Hunterston and the food chain via supplies of carbon dioxide (CO2) had ''never occurred to Scottish Nuclear or the Nuclear Installations Inspectorate.''

But he stressed ''lessons have been learned'' - and that action already taken will ensure the public health scare, arising from fears that radioactive gas had contaminated beers, soft drinks and even frozen chickens, will never happen again.

Mr Jeffrey also defended the 13-day gap between the discovery on February 20 of contamination in CO2 tank pipework at Hunterston and Scottish Secretary Michael Forsyth being informed of a potential food and drinks' hazard.

He said the link with three road tankers which could have taken away contaminated CO2 - then delivered to customers in the food and drinks industry in particular - was not made until last Friday, when further facts had to be gathered before going public.

But Mr Forsyth, in the Commons, said delays in drawing the problem to the attention of the authorities ''give rise for concern''. He has asked for a full report on the incident from the Scottish Environment Protection Agency and Nuclear Installations Inspectorate, which he expects within a week and intends to publish.

Mr Forsyth is also seeking an urgent meeting with Mr Jeffrey, and expressed ''relief'' that there appears to be no risk to public health.

His comments coincided with hundreds of people seeking advice from an emergency telephone hotline set up by the Government.

They also coincided with Opposition calls for a thorough investigation into the affair - regardless of tests so far on products revealing ''no radioactive contamination.''

There was also anger among some manufacturers named by the Scottish Office as possible recipients of contaminated supplies.

CO2 is used to cool nuclear reactors as well as to provide the fizz in drinks or as part of food cooling processes.

Mr Forsyth has now asked his officials to ''make clear'' to nuclear operators that no-one should use the same vehicles or equipment when making CO2 deliveries to nuclear installations and other locations where there may be a risk to human health.

He announced tests on products manufactured by Campsie Spring show ''absolutely no evidence whatsoever of contamination.'' Results of checks on a number of other firms' products, supervised by Sepa and the NII are still awaited.

Scottish Nuclear, welcoming the initial results, said they confirm ''there is no evidence of any radioactivity having left the power station in a delivery tanker.''

Scotland's chief medical officer Sir David Carter stressed that risks were ''negligible,'' with a food hazard warning issued only to meet possible public concern.

However, Sir David questioned why the nuclear industry does not have a dedicated CO2 delivery service.

Mr Jeffrey said new safety arrangements in place at Hunterston mean even a dedicated service is not required. From now on, CO2 deliveries will be to ''strategic reservoir tanks'' which have no gas pipe connections to the reactor.

In addition, checks will be made on tank contents to ensure no cross-contamination can occur.

The scare centres on the discovery of CO2 gas - contaminated after use to cool the reactor - slipping back into an ''operational tank'' during maintenance work on piping.

It is possible the contaminated gas found its way on three occasions into a road tanker during deliveries - in turn leading to contamination of tanks when recharging at its supply depot or during deliveries to 11 food and drink companies in Scotland. These include Irn Bru manufacturer A G Barr, Coca Cola, Allied Breweries, Alloa, and Scottish Brewers. It would appear only three of the 11 have been formally cleared so far.

First indications that a tank might be contaminated came on February 20 following measurements on pipework, according to Mr Jeffrey.

He added an incident report was made available to the nuclear inspectorate, but at that stage no connection back to the tankers or the food chain was made. Mr Jeffrey said he was told last Friday of a connection, and the NII, Sepa, and Scottish Office were informed on Monday after full calculations of possible contamination.

He said the contamination was less than a second's worth of normal background radiation, and continued: ''I believe we acted correctly and properly knowing that, if there had been contamination, it would be extremely limited.'' Meanwhile, Marshall's announced that none of the three tankers involved in the scare supplied its Coatbridge chicken plant.

Officials are clearly far from happy at being named by the Scottish Office, and it is understood legal advice may be sought given potential loss of customer confidence. It is also understood they were shocked to discover food firms are connected with nuclear installation, albeit via delivery tankers.

Barr's announced they have received written confirmation from Messer UK that ''there is no risk to Barr soft drinks.''

Tennent Caledonian Breweries revealed it was only made aware of the situation at midnight on Tuesday, with Messer UK supplying its Wellpark Brewery in Glasgow on two occasions. A Tennent's spokesman said: ''We are closely monitoring the situation.''

Coca-Cola said it was co-operating fully with the Scottish Office, and pointed to Government assurances that the risk to public health is negligible.

Birmingham-based Messer UK stressed last night there was no evidence that radioactivity left Hunterston in its tankers.

But Shadow Scottish Secretary George Robertson called for ''a full and open inquiry,'' and added: ''Where the safety of food and drink is concerned, ultra-caution must be the rule.''

Scottish Lib-Dem leader Jim Wallace said: ''Once again the nuclear industry has been responsible for an accident which will inevtibably give rise to legitimate public concern. There has to be a thorough investigation.''

Friends of the Earth said the scare was an example of ''dangerous technology and human error'' leading to widespread public health dangers.