Thames Gateway London Partnership vice-chair Conor McAuley, who also advises Newham's mayor on regeneration, said that the partnership would be wound up before the end of the financial year.
He said the decision had been taken after boroughs began to quit the group following last year's general election. "There's a new government with different priorities," he explained. "We perhaps need to articulate what we want to do through different vehicles." A bid to create a replacement, private sector-led group has already begun, he said.
The partnership had bid to establish a local enterprise partnership (LEP) for the Thames Gateway after London mayor Boris Johnson said that the case for a partnership in the sub-region was "obvious". But Johnson later decided to establish a single LEP for the city.
Alan Smith, cabinet member for regeneration at the London Borough of Lewisham, said an umbrella group for the wider area was needed. "There is no overarching strategy for east and south-east London," he said. "We've just been left to get on with it ourselves."
Selena Bolingbroke, University of East London pro vice-chancellor for strategic planning, said the body's demise would lead to the sub-region "having less of a voice in regional and national government". She said: "There is risk of a lot of bitty activity."
Smith and Bolingbroke were speaking on the sidelines of last month's East London Summit.