The Christmas toy market has become the unlikely setting for a legal row over a board game which has only recently appeared on the shelves of toy retailers nationalwide.

The National Lottery has issued proceedings against Smyth's Toys Ltd, restraining it from continuing to sell a board game entitled "Who wants to be a millionaire?" on the grounds that the National Lottery has copyright on the use of the word millionaire.

The word millionaire was registered with the Patents Office by An Post in April 1995 under classes 9, 16, 28. Class 16 covers paper and cardboard articles and class 28 covers games and playthings.

The game is a spin off from the hugely popular television game show on ITV, also called "Who wants to be a millionaire?" The show is drawing audiences of up to 18 million, making it the highest rating game show to date in the UK.

A spokesman for the National Lottery confirmed that legal action had been initiated due to issues relating to the use of the word millionaire. The lottery previously ran a scratchcard and game show with the world millionaire in their titles. The spokesman added that the matter now rests with the organisation's legal department.

Celedor in England is the producer of the show and owner of its licence and the game is made for it by Upstarts. A spokesman for Celedor has said that proceedings have been issued by the National Lottery against it and it will be "vigourously defending the matter".

Mr Padraig Smith, of Smyth's Toys Ltd, in Galway, confirmed that his company was first notified of the legal issue on Friday of last week and that it was served with a writ by the National Lottery on Thursday.

"We are now taking legal advice and considering our position and we will decide early next week what course of action to take, " Mr Smith said.

Smyth's operates a chain of stores around the country and the game has already been selling out in its nine shops. The distributors of the board game in the Republic, Jill Tyrell Distribution, has been very surprised by the National Lottery's action. "We first saw the game at the Olympia toy fair in London in January and the game has been on sale here since the end of September," said Ms Tyrell.

"Several thousand pieces have already been sold at £29.99 each and we are being contacted by customers who are taking back-orders for the game." Back-orders involve retailers promising to hold copies of the game for customers when they receive fresh supplies.

"Smyth's are the only customers on our books so far who have been the subject of legal proceedings and we have not been contacted in this regard ourselves." she said.