Gaming operator Stanley Leisure has issued a profits warning following huge losses in its core gaming and betting businesses.

The company attributed the losses in its gaming arm largely to the winning streak of a single major player, who is believed to have netted millions of pounds at Stanley’s casinos.

In a statement offered to the London Stock Exchange, it said unfavourable sporting results had also affected both Stanley’s domestic and international betting divisions.

A spokesperson said: “Whilst machine profits have continued to increase this growth has been insufficient to offset the reduction in contribution from the core betting operation.”

Shares in the company dropped around 11 per cent to 380p following the announcement. They had previously reached a six-month high of 490p during early December.

Stanley’s betting division includes 600 betting shops trading under the Stanley Racing and the new Stanleybet brands.