SCOTLAND will host the world's most ambitious rugby jamboree this week when more than 6000 youngsters from 12 nations will take part in the inaugural International Festival of Youth Rugby.

The four-day festival, which gets underway with a Murrayfield opening ceremony today, has attracted 273 teams who will play at 26 venues throughout the country, culminating in grand finals day on the main pitch at Murrayfield on Friday.

Scottish Rugby Union patron, the Princess Royal, will attend the finals and present trophies and medals to the winning sides.

The response from the world-wide rugby community has been such that it has now been decided to make the tourney a bi- ennial event.

The tournament is the brainchild of former Glasgow Academicals hooker Dr Ronnie Graham. The tournament chairman is Sports Council chairman Graeme Simmers - another with Glasgow Accies connections - and Peter Lavery, who is also involved in the youth section at New Anniesland, has been working full-time as tournament director since last October.

Lavery said: ''It is fantastic to see our plans coming to fruition. It has been a major logistical exercise and we calculate that over the four days, there will be 1628 games involving 273 teams from 189 clubs and schools.

''There are more than 6000 youngsters taking part and they will be accompanied by parents and supporters.''

Teams are taking part from the Five Nations' countries, South Africa, Switzerland, Portugal, Latvia, Georgia, Romania, and Italy. The tournament will be run on an age-group basis, with five divisions ranging from under-12s to under-16s.

The 26 playing sites are in Glasgow, Edinburgh, St Andrews, Perthshire, Dundee, Stirling and the Borders. The youngsters will be accommodated locally and mainly in university halls of residence and in boarding schools.

The first two days of the tournament will be taken up with qualifying matches to be followed by quarter and semi- finals on the back pitches at Murrayfield, and all five finals will be played on the hallowed turf of the Test pitch in the main stadium.

Lavery declared: ''We have worked hand-in-hand with the Scottish Rugby Union who have given the tournament their full blessing. It was their director of rugby, Jim Telfer, who took our proposals to the union and I must say they have been absolutely superb.''

The tournament schedule also provides a programme of entertainment for the children and their supporters. A rock concert will be staged at the Ingliston Exhibition Hall tomorrow and this will be followed by a fireworks display. Simultaneously, a party will be thrown for accompanying adults in the McRobert Pavilion at Ingliston. There are also events planned at each of the playing locations.

Lavery said: ''We have been working on the proposals for almost two years now. Things started very slowly. Initially, we circulated every club and school in the UK but the re sponse wasn't great. I think that most club secretaries just threw the invitation into the paper bin.

''We then contacted all of the rugby development officers throughout the country and it really started to take off. We're delighted with the level of participation we've now achieved - so much so that we will do it on a two-yearly basis. We're now raring to go.''