Mayor of London Ken Livingstone has been asked to clarify whether long-overdue plans for major improvements to the North Circular Road have a future or whether they will be replaced by a watered-down scheme.

Transport for London commissioner Bob Kiley recently told Leo Boland, Barnet Council's chief executive, that, following last month's Treasury spending review, the proposed £800million scheme to improve the A406 junctions at Henlys Corner and New Southgate was unlikely to proceed. Instead, a much smaller scale improvement would have to suffice.

Brian Coleman, Tory Barnet councillor and chairman of the Greater London Assembly, has written to Mr Livingstone asking him to renew his support for the project.

"The reserve scheme is unacceptable to the four London boroughs concerned," he said.

A spokesman for Transport for London said: "Some hard decisions will have to be taken following the spending review but these decisions have not, at this stage, been taken. We will be talking to local stakeholders about which plans to take forward."