SCOTLAND'S oldest working monastery, on the southern shores of Loch Ness, is to close after having been a centre for devotion and prayer for 122 years.

Declining numbers among the Benedictine order and buildings deemed ''too large . . . and expensive to maintain'' have been blamed for the closure of Fort Augustus Abbey.

The abbey was a private school for boys until 1993, when dwindling numbers forced its closure. The monks turned to tourism the following year, opening the doors to the public in a bid to pay for the upkeep of the historic abbey. However, the business venture proved unsuccessful.

A statement issued yesterday on behalf of the Community of St Benedict's Abbey said ''disappointingly poor'' tourist seasons in the past two years had precipitated the decision of the monastery's commercial arm, Fort Augustus Abbey Enterprises, to stop trading.

It will close its 80-bed accommodation blocks, tourist and heritage centre, and restaurant as well as the Celtic craft shop and mail-order business.

The 10 monks who remain are likely to seek positions within the order in England and Scotland. Around 50 local people who were employed at peak periods during the tourist season have been told of the proposed shutdown.

The Rev Francis Davidson, the prior administrator at Fort Augustus, last night said the decision to close the monastery had been a very painful one for all monks concerned, for the people they employed, and for the local community. He added: ''It is a sad day for all of us, both that we are leaving our home for so many years and also that we are not going to be involved in the life of Fort Augustus and the Highlands.

''We are pleased, however, to have made a useful contribution over the last 100 years to the Highland community, and to the Catholic Church in the Highlands.''

The land was given to the monks by Lord Lovat for educational and religious use for a peppercorn rent in 1876. It is believed the order was latterly paying rent of about #1 a year.

The abbey's beautiful grounds, including a tree-lined cricket pitch, and the buildings will revert to Lovat Estates. The estate is now actively involved in what will happen to the abbey and grounds. The abbey sits on one of the most picturesque pieces of real estate in the Highlands.

It has been suggested the buildings may be taken over for a major commercial development such as a luxury hotel or country club.

The Bishop of Aberdeen has been kept informed of developments and has expressed his wish to ensure the continuity of a local parish church and community in Fort August village.

The Community of St Benedict's Abbey statement said: ''The monastic community resolved at a meeting of November 17 and 18 that they should start the process of closing the monastery. The community numbers have been declining over the years.

''The present numbers make it very difficult to maintain the full round of monastic life. In addition, the buildings are now too large for the current community and too expensive to maintain.''

Ms Alison Sharp, marketing manager with Inverness and Nairn Enterprise, expressed concern at the decision but added: ''In the longer term, we are confident that this magnificent site located at the south end of Loch Ness offers great potential for a more commercially focused operation.''

Fort Augustus councillor Pat Paterson described the closure as ''a blow''. However, he said the council remained optimistic that the valuable abbey site would be put to good use for the benefit of the community.

The monastery was founded in 1876 in the remains of the old Hanoverian fort which were owned by the 14th Lord Lovat. The fort was built between 1729 and 1742 by General Wade and was occupied by the military until the Crimean War in 1856. Lord Lovat bought the buildings from the Government in 1866, leasing them back to the Benedictine order 10 years later.

The Benedictine order also runs Pluscarden, one of Scotland's two remaining monasteries, near Elgin in Moray. The other monastery, Runraw, is operated by Cistercian monks, near Haddington, Midlothian.