The Abu Dhabi Investment Authority (ADIA) has agreed to join Morgan Stanley and private equity group 3i in a bid for the high-speed railway linking London with the Channel Tunnel, Abu Dhabi's National newspaper said.

State-owned ADIA, considered the world's largest sovereign wealth fund, is in the 'very early stages' regarding its involvement in the bid, the paper said, citing a source close to the sale process.

The sale process could fetch 1.5 billion to 2 billion pounds ($2.34 billion to $3.12 billion) according to the paper.

An ADIA spokesman declined to comment when contacted by Reuters.   

The sale of the 110-km High Speed 1 (HS1) line, which links central London to the Channel Tunnel, will be the first major British transport infrastructure sale since airport operator BAA sold London's Gatwick airport late last year.   

ADIA bought a 15 percent stake in Gatwick Airport earlier this year.

Britain began the sale of the rights to operate the country's only high-speed railway in June, helping raise much-needed funds for the public purse.
   

Other bidders include Channel tunnel operator Groupe Eurotunnel SA which is working on a bid with Goldman Sachs Infrastructure Partners, its biggest shareholder, and with Infracapital, the infrastructure arm of Prudential unit M&G, another big shareholder. - Reuters