LONDON, May 6 (Reuters) - Ferrovial, the owner of Heathrow airport, is in advanced talks to buy 3i's Enterprise, Britain's biggest street-sweeping company, in a 500 million pound ($808 million) deal, the Sunday Times reported.
The Madrid-based infrastructure giant wants to buy Enterprise and merge it with Amey, its British engineering subsidiary.
3i declined comment when contacted by Reuters and no one at Ferrovial could be reached immediately for comment.
Enterprise is the biggest provider of services such as street cleaning and waste collection to councils and utilities. It has more than 3,000 staff.
The outsourcer was bought for 700 million pounds in 2007, making it 3i's biggest investment in Britain.
But the acquisition turned sour as the private equity company struggled to cope with the company's huge debt burden.
It was forced to write down the equity value of Enterprise to zero last year. ($1 = 0.6189 British pounds) (Editing by Hans-Juergen Peters)