Littlewoods has now complained to the Office of Fair Trading, saying its concerns are supported by other charities.

In a five-page letter, Littlewoods says Camelot threatened to disconnect on-line lottery terminals if newsagents and other retailers stocked Littlewoods' and other rival scratchcards.

Camelot's scratchcards are the market leaders

The pools company, which entered the scratchcard market in 1994, sells a wide range of lottery-style cards linked to well-known charities like the Imperial Cancer Research Fund, Age Concern and the Great Ormond Street Hospital.

Littlewoods says more than 30 organisations have sent letters supporting its complaint and voicing concern about Camelot's tactics.

Camelot has denied that it has any policy of intimidating retailers and said that any complaints against it would be investigated internally.

A spokeswoman for the lottery operator said: "Camelot's policy is clear. We in no way discourage retailers from selling competitive products. If anyone has any proof that this is not being followed we will investigate it thoroughly.

"Ultimately decisions about which products to stock are made by individual retailers."

Highly competitive

Littlewood says it has gathered written and verbal evidence to support its accusations and believes that "even the most powerful retailers are unwilling to jeopardise their ability to receive National Lottery on-line terminals".

The scratchcard business is highly competitive. Littlewoods has only a 3.5% share of the market, while Camelot controls more than 95%.

Littlewoods has raised the issue of Camelot's own scratchcard games once before, with lottery regulator Oflot.

The company alleges that Camelot is subsidising its scratchcard games with proceeds from the main lottery operation.

However, according to Littlewood the regulator was "not ... supportive".