US - The California Public Employees' Retirement System (CalPERS), the largest pension fund in the US, has agreed to buy a stake in a 65-mile underwater power line along the East Coast.

The terms of the deal were not disclosed.

The Sacramento, California-based pension fund, which has $255bn (€196bn) in assets under management, bought the stake in Neptune Regional Transmission System from Arclight Capital Partners.

Neptune Transmission owns the 65-mile undersea and underground electric power line that runs from New Jersey to Long Island, New York.

The deal between CalPERS and Arclight, an energy investment firm with roughly $10bn in investments, is expected to be completed in the first quarter of 2012, CalPERS said.

This is the second direct infrastructure investment by the pension fund following the 2010 purchase of a 12.7% stake in London's Gatwick Airport.

CalPERS chief investment officer Joseph Dear said the investment was consistent with the fund's long-term plans to boost investment in infrastructure.

"It's an income-generating investment with stable revenues located in the US, very much in line with the type of investment we said we would be looking to make when we described our vision for infrastructure in September," he said.

CalPERS plans to invest as much as $5bn in infrastructure projects, $4bn of which will be in the US and as much as $800m in California.

The pension fund plans to invest in both public and private infrastructure, including but not limited to transportation, energy, natural resources, utilities, water communications and other social support services.

Neptune Transmission - which began construction in June 2005 and completed in June 2007 - provides as much as 660 megawatts of power to Long Island's electricity consumers, accounting for more than 20% of its electricity demand.