Airtricity, a subsidiary of Dublin-based toll road operator and infrastructure developer NTR, has agreed terms for a takeover by leading UK energy supplier Scottish & Southern Energy.

The deal, which includes all Airtricity's interests in the Republic, the UK, North America and on the Continent, is worth a total of €1.8bn (£1.34bn).

NTR had announced in October that Airtricity was being put on the market, and initially German company E.On was regarded as the front runner.

The sale will lead to a massive windfall for the company's founder, Eddie O'Connor, and investors who backed his green vision.

Jim Barry, chief executive of NTR and chairman of Airtricity, said the sale was an important milestone, and was in the best interests of the company and its shareholders.

"This announcement will secure Airtricity's position as a world-leading renewable energy company as part of a large electricity utility," he said.

"NTR is pleased to have been part of the growth and development of Airtricity since our initial investment in 1999 and we are pleased that its future development has been secured."

Airtricity operates wind farms in Fermanagh and Tyrone, with its facilities at Tappaghan, near Kesh, and Bin Mountain, near Castlederg, providing sufficient electricity to power 17,000 homes.

The company has secured planning approval for six more installations in Northern Ireland and is also proposing a renewable scheme in China.

As well as onshore wind farms across the Republic, Britain and Portugal, Airtricity operates off-shore farms around the British Isles and off the coasts of Germany and the Netherlands.

The takeover follows Perth-based SSE's purchase of Airtricity's US business unit last year, and the combined purchase price includes payment for the proceeds from that deal.

The transaction is expected to be completed by the end of the current financial quarter, subject to conditions and regulatory approval.

Ian Marchant, the chief executive of SSE, said: "The combination of SSE's and Airtricity's interests in renewable energy will provide an excellent platform for future growth."

He said SSE would benefit from the "strong expertise and enterprise" of the Airtricity team, which comprises more than 300 staff based in Dublin, Omagh and elsewhere.

Mr Marchant said Airtricity would continue to operate from Dublin under its existing name as a distinctive business within the SSE group.