Britain's biggest construction company Balfour Beatty
A spokeswoman for the London-based company, which developed the city's Olympic Aquatics Centre, is cited as saying all 12,000 staff in the construction services division had been notified, but did not specify how many jobs would be at risk.
The company, which employs 50,00 people worldwide, is quoted as saying it was conducting a consultation process to align the resources of Balfour Beatty's Construction Services UK business to current and future market conditions.
The threat of redundancies come amid a savage downturn in the construction industry that has seen builders wages drop dramatically since the onset of the financial crisis in 2007.
Balfour Beatty could not be reached for immediate comment.
(Reporting by Stephen Mangan; Editing by Michael Perry)