A rival bid to the Lloyds HBOS merger will be made public within a week, according to an MSP opposed to the government-brokered deal.

Alex Neil of the SNP, Liberal Democrat leader Tavish Scott and independent MSP Margo MacDonald yesterday called for the proposed deal to be halted until shareholders, who have yet to vote on the merger, have all possible information before them.

Mr Neil said he expects a fresh bid to be finalised and revealed next week - one that would not require large sums of government cash and would retain corporate offices in Scotland, leading to fewer job losses.

As the financial sector awaits a resolution to the HBOS troubles, politicians of all parties have accused one another of political posturing while thousands of jobs are at risk.

Expectation has grown over former HBOS executive Jim Spowart fronting a consortium bid to take over HBOS, following talks with Scottish Secretary Jim Murphy.

Mr Murphy said that he had discussed the possibility with the Treasury, which has said it will consider any new bid.

Tavish Scott said he met Jim Spowart and LibDem UK Treasury spokesman Vince Cable earlier this week to discuss the possibility of a bid.

Labour leader Iain Gray told opponents of the Lloyds TSB deal that an independent HBOS seemed unrealistic and called for potential bidders to bring forward proposals for examination.

Mr Neil said the Lloyds TSB deal was not in the interests of employees, shareholders or Scotland, and called for the chairman and chief executive of HBOS to resign for pressing ahead with it.

He said they were duty bound to consider all possible alternatives in the interests of the shareholders and to speak to others considering a bid.

Mr Neil said: "I am confident that in the next week at least one rival bid will be made public."

He added: "Jim Spowart is on record saying if the rival bid comes off they won't need any significant injection of public capital. I find it amazing HBOS are not looking at rival bidders."

Mr Scott said the deal was a takeover and not a merger. He added: "HBOS and Lloyds TSB are moving ahead at pace. When Gordon Brown met with Lloyds TSB there was no bank bailout on the table. When that changed the deal became open to question. There is nothing that precludes directors from looking into the options."

Margo MacDonald said: "We must try to hold on to the corporate functions on the Mound, and minimise job losses. There will be rationalisation, there will be some shake-out but it won't be as drastic as 20,000 jobs."

Labour and the Conservatives criticised the three MSPs over their opposition to the merger.

Mr Gray said: "For over a month now Alex Neil has being going on about an alternative bid. It is time he said who they are and they came to the table.

"It is irresponsible to raise hopes if there is in fact nothing concrete there. It is outrageous to use thousands of people's jobs as political pawns in what looks increasingly like political posturing."

Annabel Goldie, Scottish Tory leader, said: "Unless Tavish Scott, Alex Neil, and Margo MacDonald are bringing forward their own bid for HBOS there is no other bid.

"For them to urge HBOS shareholders to reject the only bid on the table is utterly irresponsible political posturing at its worst.

"Alex Neil is clearly seen as Alex Salmond's proxy sent to scupper the HBOS rescue. That is a dangerous position for a First Minister to take."

Ms MacDonald retorted: "The success of Edinburgh as a city is being jeopardised by politicians who are using it as a club to beat the argument for independence about the head. We are ill-served by politicians who do that."