A view of part of Heathrow Airport near London. [REUTERS/ STEFAN WERMUTH]

British Prime Minister Theresa May, faced with an increasing need to boost aviation capacity in the southeast, is expected this week to pick Heathrow Airport, in which China Investment Corp has a 10 percent stake, as the site for extra runway capacity, analysts say.

The decision will be announced in the House of Commons by Transport Secretary Chris Grayling on Tuesday, but will not be followed by an immediate debate.

Instead, there will be more public consultation, with a parliamentary debate scheduled for before the start of 2018.

The issue is a political hot potato, with aviation experts telling the government an extra runway is needed at either Gatwick, south of the capital, or Heathrow, to the west, the main airport. Environmentalists question the need for any expansion.

Last week, May's office said she would chair a small group of ministers to decide which airport would be chosen. She has given ministers opposed to the Heathrow plan, including Education Secretary Justine Greening and Foreign Secretary Boris Johnson, permission to air their views for a specified period, a clear indication Heathrow is the preferred option.

Both have constituencies bordering the airport, and Johnson recently told opponents of the expansion: "I will lie down in front of those bulldozers with you to stop the building."

But the Sunday Times predicted neither he nor Greening would resign over the issue.

There have been calls for extra capacity at Heathrow for almost 30 years and successive governments have delayed decisions or called for enquiries, but the subject has become increasingly important with growing passenger traffic. Both Heathrow and Gatwick are operating close to capacity, with an aircraft landing or taking off at Heathrow every 45 seconds.

Last week, China and the UK agreed to increase the number of flights between the countries to 200, with two Chinese carriers－Hainan Airlines and Tianjing Airlines－saying they would consider more flights.

Gatwick started as a hub for holiday charters and low-cost carriers but has recently been served by international scheduled airlines. Most foreign carriers prefer coveted landing slots at Heathrow.

Gatwick says construction there would impact fewer people and cost less than the estimated 17 billion pounds ($20.8 billion) for Heathrow's expansion.

Last year, an independent Airport Commission decided that Heathrow should get the extra capacity, but the then-prime minister, David Cameron, called for further environmental studies.

In the wake of June's referendum in which Britons voted to leave the European Union, much weight has been attached to airport expansion, which the government sees as reassuring overseas investors that Britain is "open for business".