London Stock Exchange Chief Executive Xavier Rolet was under pressure on Thursday after the Maple consortium of banks bidding against him to buy Canada's TMX Group raised its offer overnight.

The British exchange, which on Wednesday announced a special dividend for its own and TMX shareholders in an effort to boost support for its merger, now faces a tough decision after Maple reacted quickly by nudging its bid ahead of the LSE's.

Maple, which is backed by 13 of Canada's largest financial firms, said early on Thursday it had raised its bid to C$50 a share from C$48 a share and increased the number of shares it wanted to 80 percent from 70 percent.

A spokeswoman for the LSE declined to comment on Thursday. Shares in the British exchange were down 0.6 percent in early trading, as the onus fell back on the LSE to react to Maple's latest move.

If the LSE don't get TMX then someone's probably going to come and bid for them, said one of the LSE's 50 largest shareholders.

A failure by the LSE to secure the Canadian exchange group could leave the British exchange a takeover target itself, possibly for Nasdaq OMX which has tried hostile takeovers of the LSE twice in the past five years.

(Editing by Erica Billingham)