The Abu Dhabi Investment Authority is looking at bidding for the Channel Tunnel high-speed rail link.
The world's biggest sovereign wealth fund is reportedly working with Morgan Stanley and 3i, the private-equity group, to make the bid.
The sale of the 68-mile High Speed One (HS1) link between London and the Kent coast started in June and is expected to make up to £2bn to help to shore up Britain's debt-wracked public finances.
The deadline for submitting an offer for HS1 is 17 August. If the Abu Dhabi Investment Authority makes a formal bid, it will be in competition with Groupe Eurotunnel, backed by two major shareholders: Goldman Sachs Infrastructure Partners and Infracapital, the infrastructure arm of M&G. Groupe Eurotunnel already runs the Channel Tunnel itself.
The successful bidder will be expected to open up HS1 to new train operators.