LONDON (REUTERS) - Burberry is attempting to identity a mystery investor who has built up a stake of nearly 5 per cent in the company, pushing its shares to a five-month high on Tuesday on speculation of a potential takeover bid.

The company is reported to have asked HSBC, which is listed as the custodian of the stake, to reveal the identity of its client, according to a report in the Financial Times.

An investor building up a stake could put pressure on the British firm, whose market capitalisation has fallen in the past year amid concerns about falling demand from its key markets in Asia, particularly China and Hong Kong.

A source close to the company said Burberry was focused on the stake and keeping a close watch on it but there had been no formal takeover bid made.

Burberry has spoken to its financial advisers Robey Warshaw and Morgan Stanley about the growing stake, which broke a 5 per cent barrier recently but was now just below the threshold.

Shares in the company jumped by more than 5 per cent in early trading, and were 4 per cent higher at 1434 pence (S$28.09) by 1005 GMT, making it the biggest gainer on the FTSE index.