TMX Group confirmed that it has received a bid from the group of four banks and five pension funds under the name Maple Group Acquisition Corporation. Maple is offering C$48 a share, 70% in cash and the rest in shares, trumping the LSE agreement struck in February.

Any deal would hang on regulators giving the green-light to a merger between TMX and Alpha Group, an alternative trading system owned by Canada's banks and the Canadian Pension Plan Investment Board. In addition, Maple says TMX would also have to get permission to merge with the bank-controlled clearing system CDS.

TMX Group says that "in accordance with its fiduciary duties and with counsel from its financial and legal advisers, [it] will fulfil its legal responsibility and will evaluate the proposal".

However, it also stresses that it will carry on working to get regulatory and shareholder approval for the LSE merger.

News of the bid comes as little surprise as opposition to the tie-up has been mounting in Canada, with banks penning a letter in March outlining their concern that the deal would hurt Toronto's ambitions to become a global financial services hub.

If the banks succeed in thwarting the LSE's plans, it will prove a serious setback for the London bourse's ambitions during a period of consolidation that is also seeing Deutsche Boerse battle it out with Nasdaq OMX and IntercontinentalExchange (ICE) for control of Nyse Euronext.

The Maple members are understood to be Toronto-Dominion Bank, Bank of Nova Scotia, Canadian Imperial Bank of Commerce, National Bank of Canada, Caisse de Depot et Placement du Quebec, Canada Pension Plan Investment Board, Ontario Teachers' Pension Plan, Alberta Investment Management and Fonds de Solidarite des Travailleurs du Quebec.