Ministers were condemned yesterday as "not up to the job" of managing the huge Thames Gateway regeneration project to build 160,000 new homes and create 180,000 jobs.
Members of an all-party parliamentary committee warned the programme remained "little more than a group of disjointed projects" and that immediate action was needed to prevent "another public spending calamity".
They said that without "vastly" improved management, it would fail to fulfil its potential for regenerating the economy.
But the Department for Communities and Local Government angrily rejected the report, insisting it was out of date.
Estimates suggest the Thames Gateway programme could add £12bn a year to the economy and create a significant proportion of the new homes needed to meet demand in the South-east by 2016.
But the powerful Commons Public Accounts Committee said the department had failed to put in place basic arrangements for managing the developments. MPs warned that the department carried little clout in Whitehall, comparing it to a "small child clamouring for the attention of its bigger classmates".
They warned the department did not have a full budget for its work on the Thames Gateway and does not know how much the project will cost the taxpayer.
Edward Leigh, Conservative chairman of the committee, said: "The department ... is manifestly not up to the job of managing the enormously ambitious enterprise of regenerating the Thames Gateway region. Action must be taken now to prevent the enterprise ending in another public spending calamity.
"The department has been incapable of taking the multitude of central, regional and local partners in the scheme to work together to turn it into reality."
The Government has spent £673m so far on redeveloping the area from Canary Wharf to the mouth of the Thames at Southend-on-Sea, one of the most deprived areas of the South-east.
But the MPs warned: "It is unclear how the department's management of the programme has added value to the projects that they fund." They said the department had failed to set proper targets for the progress of the project and called on ministers to make annual reports to MPs.
A Communities and Local Government spokeswoman said she did not recognise many of the assertions in the report.
She said: "The pace of change in the Gateway is such that the PAC report is already out of date.
"In the last 12 months alone, Government investment and intervention have delivered major progress, with the opening of two international stations on the High Speed Rail Link, agreement on Crossrail which will substantially benefit Canary Wharf and Woolwich and major progress on the Olympic developments and at Stratford. These alongside the new port at London Gateway are the very projects the Thames Gateway partners identified as the major drivers for regeneration and investment."Reuse content