Speculation is rife that Associated Newspapers may look to fill the gap left by the closure of the News of the World with some sources even claiming that test runs on a title were carried out over the weekend.

A source said: "The focus at the moment is to ensure that the Mail on Sunday is in the best position possible to make the most of the gap in the market.

"Of course they are looking at their options as any media company would; the rumours are not without merit."

Associated Newspapers declined to comment on the situation.

The week prior to the News of the World's closure the red-top market claimed 51% of the Sunday market, while the middle market, which is dominated by the Mail on Sunday, had a 27% share.

During News of the World's final week the results became skewed, but last weekend the red tops dropped to 43% and middle market increased to 34%.