The party is trying to halt the reduction in the number of MPs from 650 to 600.
Experts suggest that the changes could see Labour lose between 24 and 30 seats – including that of Labour leader Jeremy Corbyn, who would see his Islington North constituency disappear.
Labour is seeking a new review of boundaries which would keep all 650 MPs, but perhaps change the shape of seats.
But officials have now calculated that the cost of such a review would be £8million, even before the salaries and expenses of an extra 50 MPs and their staff were included.
A Tory source said: “Labour wants to spend £8million of taxpayers’ money just to save its own seats.”
Labour hit back at the accusation. Cat Smith, the party’s shadow minister for voter engagement, insisted some Tory MPs were opposed to the current boundary review.
She said: “Theresa May and the Tories have further increased the cost of politics by adding 260 unelected peers to the Lords since coming to power.
“That works out at a cost of around an extra £34million every year.”
John O’Connell, chief executive of the TaxPayers’ Alliance, said: “It’s upsetting, though unsurprising, that once again politicians are using taxpayers’ money to play politics.”
He added: “The boundary review was apolitical for a reason – to stop either side from taking advantage of the process. The political class should remember that throwing our money around for their benefit is the main reason that they are so mistrusted by the public.”
Both Labour and the Tories have accused each other of attempted gerrymandering.
Last week the Commons was told British MPs represent an average of around 90,000 people, while that figure is 133,000 in Spain and 116,000 in Germany.