LONDON, Dec 6 (Reuters) - TUI, Europe's biggest travel operator, said on Wednesday it was considering leaving the London Stock Market and upgrading its listing in Frankfurt, where trading in its shares has increased significantly and more of its investors are based.

The move, which could be put to shareholders in February, would be a blow to London after Britain's biggest chip company ARM floated in New York this year and building supplies firm CRH and plumbing equipment company Ferguson shifted their main listings to the United States.

Hanover-based TUI's dual listing stems from the merger of its holiday business with Britain's First Choice Holidays in 2007 to create London-listed TUI Travel. Seven years later, the companies fully merged.

It said it had been approached by some of its shareholders to discuss whether it would be better to move to a single Frankfurt listing, where it would join the MDAX index of companies beneath the top ranking DAX.

TUI, which noted it had seen a shift in the trading of its shares to Germany, said the move could result in a clearer investment profile, potential benefits to European Union airline ownership and control requirements, and reduced costs.

It said it was considering putting the change to shareholders at its AGM on Feb. 13. At least 75% of the votes cast would need to be in favour to trigger the move.

The company said a London delisting would have no impact on its image with British consumers.

Shares in TUI rose 8.5% in Frankfurt and 8.4% in London in early trading on Wednesday after it forecast a 25% jump in operating profit in its new financial year. (Reporting by Paul Sandle Editing by Mark Potter)