THE Scottish Office has confirmed that radioactive waste was secretly dumped off Scotland in the 1950s.

The admission comes after years of controversy over the dumping of munitions at Beaufort's Dyke in the Irish Sea.

An action group was set up early last year involving authorities on both sides of the Irish Sea because of concerns over the dumping of more than one million tonnes of munitions in the past 70 years.

For the past 13 years Ministers have officially denied that waste was secretly deposited in a 300-metre deep munitions dump close to busy shipping lanes six miles off the coast.

Now the Ministry of Agriculture, Fisheries and Food (Maff) is expected to make a formal announcement - perhaps as early as today - that the dumping of low to intermediate-level contaminated waste did take place in Beaufort's Dyke in the 1950s.

A Scottish Office spokesman last night said: ''This is for Maff to respond to in detail. Prior to this discovery successive governments were not aware that such materials were dumped there.

''At present officials are trying to ascertain precise details of materials and quantities before a full announcement is made shortly by Maff.

''It is emphasised that what we are talking about is a very small quantity of material with likely levels of radioactivity which are so insignificant that they cannot be measured.''

A Maff spokesman refused to comment when contacted by The Herald early this morning.

A report in the Guardian newspaper claims that the Government will today own up to the dumping of radioactive waste in Beaufort's Dyke.

The newspaper says official papers to be released will reveal that the Scottish Office authorised the dumping of low level waste from private companies, including defence contractors Ferranti, during the 1950s and the early 1960s.

It adds that up to two tonnes of waste, in heavy metal drums encased in concrete, were dumped in Beaufort's Dyke - a seven-mile munitions dump used by the Ministry of Defence since the 1920s. The extent of the dumping has still to be fully investigated by the Government.

Ministers believe the dumping presents no danger to the public, following attempts to monitor radiation levels by Maff. The waste comes from laboratories and from luminous paint and clock dials. Most of it is thought to be from civilian sources.

As recently as December Scottish MPs walked away happy with safety assurances about the laying of electricity and gas links across Beaufort's Dyke to Northern Ireland.

The Scottish Environment Minister at the time, Lord Lindsay, told MPs that the planned ScottishPower interconnector to transmit power across the sea would be diverted around munitions that had been dumped in the area.

The Health and Safety Executive insisted there was a one in a trillion chance of the gas pipeline and munitions causing an accident.

No exploration for gas or oil would be allowed in the area without a detailed survey.

A final decision on the controversial plans to build the electricity interconnector between Scotland and Northern Ireland is due to be announced next month.

A Government source said last night that information on the secret disposal of radioactive waste had been in the public domain for some time. ''It is only now that the Government has got round to publishing anything on it,'' he added.