THE first hi-tech sweep of a Scottish loch gets underway today in search of its little- known resident ''monster''.

The mysterious beast, dubbed ''Lizzie'', is said to have been spotted twice in recent months in 10-mile-long Loch Lochy, in the Great Glen north of Fort William.

It has sparked off interest among phenomena enthusiasts more accustomed to searching the depths of Loch Ness.

One group now is switching its attention to Scotland's third deepest loch and will begin a sweep of Loch Lochy from a boat using sonar equipment and an underwater microphone.

The search team expects to build up a picture of the underwater features of the loch and hopes to find rock overhangs or caves where ''Lizzie'' could be lurking.

The team includes members of the Official Loch Ness Monster Fan Club, independent researcher Richard Carter, together with sub-aqua members of Darlington Dive Club, and representatives of a delegation of experts on the paranormal which explored Loch Ness this summer.

Fan club president Gary Campbell, who is organising the sonar sweep, said: ''The underwater microphone we are using is very sensitive. It can pick up the sound of a chain rustling from over a mile away.

''We are trying to establish if there are any hidden caves where the monster can hide.

''It is possible that there are similar geographical anomalies such as the 'Edward's Deep' which was found 850ft down on the floor of Loch Ness earlier this year.''

Last February, local gamekeeer Alasdair Stevenson was fishing for pike on Loch Lochy when he claims that a 20ft black-skinned creature leapt out of the water and took the hook, line, sinker and half of the rod clean away from him.

At the time, he said: ''It was like catching a rowing boat.''

In September 1996, two staff at the Letterfinlay Hotel, which overlooks the loch, saw a strange aquatic monster zig-zagging across the water and claimed that it was definitely not a fish.

The workers told coll-eagues and guests about the sighting and a total of 18 people saw the dolphin-sized creature breaking the surface.

There have been sporadic reported sightings of a monster in Loch Lochy since the last century.