SKANSKA is believed to be considering strengthening its ties with McNicholas Plc after working with the civils specialist on a major gas contract.
The pair are working on the £400 million North London Gas Alliance under an eight-year deal.
A source said both companies were keen to expand the joint venture into PFI and other utility works.
He added: 'Skanska has the financial muscle and Brown Macs have the utility expertise. They're looking at elements of PFI where it involves infrastructure.
'They're looking at working together more, due to the success of the London alliance. But nothing has been concluded on these discussions.'
Brown Macs shut its loss-making civil engineering and building businesses two years ago to focus on power, highways, gas and transportation.
Last year the firm saw like-for-like pre-tax profits jump from £410,000 to £4 million.
Chairman Bernard McNicholas, who turned 65 this year, has long since handed over day-to-day running of the business to Michael Doherty.
Speculation has been growing that Mr McNicholas is looking to sell his majority shareholding. One source said: 'Bernard has very little involvement in the firm nowadays. He spends a fair bit of time over in Ireland.'