BRITISH Energy, which is looking for nuclear power plants in the US, may buy into Three Mile Island which suffered the United States' worst-ever nuclear accident in 1979.

A British Energy source said yesterday the company was still in discussions with GPU, the US generator which owns Three Mile Island in Pennsylvania and another nuclear power station at Oyster Creek in New Jersey.

But the source stressed that British Energy was also talking to several other US electricity companies with nuclear power plants for sale. ''It is very early days, but we do have discussions ongoing with a number of companies, including GPU,'' the source said.

British Energy, which was privatised two years ago, runs eight nuclear power stations in the UK. These include Hunterston B and Torness in Scotland.

Last year, the Edinburgh-based company formed a joint venture with Peco Energy of Philadelphia called Amergen to acquire and operate nuclear powers stations on the Eastern Seaboard of the US.

It is also negotiating separately to buy a controlling stake in the 19 nuclear power stations of Ontario Hydro in Canada.

Reports that Amergen was interested in Three Mile Island first surfaced in October, but British Energy officials said then that the infamous power station was not at the top of their shopping list.

The fact that Amergen is still talking to GPU eight months later, suggests that British Energy may now be looking at Three Mile Island more seriously.

There are two reactors at the power station on the Susquehanna River.

One was shut down permanently after the accident in 1979. The reactor overheated after losing coolant water and appeared in danger of meltdown at one stage as radioactive gases leaked into the atmosphere. But the other remains in operation and today ranks as one of the 10 most efficient nuclear power plants in the US.

It is this second reactor and GPU's other nuclear power station at Oyster Creek that Amergen is eying up.

But it is not clear whether British Energy and its US partner would be able to buy the working reactor at Three Mile Island without taking responsibility for the dud as well.

And even if such a split could be secured, would British Energy shareholders feel happy with it?

In the UK, British Energy already shares the ownership of some nuclear sites with the Government.

At Hunterston on the Clyde for instance, British Energy controls the operational Hunterston B reactor, whereas the older and now decommissioned Hunterston A reactor next door is the responsibility of Magnox Electric, a Government agency.

However, Hunterston A shut down at the end of its natural life, not because a major accident forced its premature closure.

Whatever the legal guarantees negotiated with GPU and the US authorities, British Energy might face big difficulties persuading its shareholders to accept a deal that would make it either the owner or the neighbour of Three Mile Island's nuclear cemetery.

A spokeswoman for the company declined to comment on a report in yesterday's Observer that British Energy was poised to buy Three Mile Island and that GPU was was now talking exclusively to one would-be buyer for both Three Mile Island and Oyster Creek with the aim of concluding a sale within six to eight weeks.

''We are talking and have been talking for some time to a number of American facilities and at the moment we have no formal statement to make,'' she said, adding that shareholder value would be the ''paramount'' consideration of any deal.

The British Energy source described the Observer report as ''extremely premature,'' and dismissed out of hand the idea that a deal with GPU might be struck in the next eight weeks.