A spokesman for LDI, a consortium which last week took over London Transport Advertising, said the ban on advertising would not be lifted.
'There will be no political advertising. It has been written down in our terms and conditions,' he said.
Labour expressed concern that political advertising would be allowed after an LDI spokeswoman confirmed the policy might change. But LDI said yesterday the remarks were unauthorised.
A spokesman for London Transport, which sold LTA to LDI, said London Transport still owned the sites, and would not allow them to be used for political advertising.