BRUSSELS, March 20: EU transport ministers are to give clearance on Thursday for plans to open up the transatlantic aviation market to tougher competition unless Britain throws a spanner in the works.

After four years of discussions, a so-called "open skies" agreement is in takeoff position after EU and US negotiators hammered out a tentative deal at the beginning of the month to liberalise transatlantic air traffic.

The European Commission, which negotiated the deal on the EU's behalf, says consumers will see up to 12 billion euros ($16 billion) in economic benefits as increased competition brings downs ticket prices.

However, Britain has deep reservations about the deal because it would lift restrictions on the number of airlines that can fly lucrative transatlantic flights from Heathrow airport outside London, the busiest in Europe.

Currently, only British Airways, Virgin Atlantic of Britain and US carriers United Airlines and American Airlines are allowed to fly from Heathrow to the United States.

British Prime Minister Tony Blair is to hold a video-conference on Tuesday with US President George W. Bush in a last minute effort to get special treatment for Heathrow, several well informed sources said.

If the so-called "open skies" agreement on the table gets the EU ministers' backing, it is expected to go into effect by Oct 28.

However, London is aiming to get a transition period for Heathrow running to May 2008, when a fifth terminal is due to open, one EU source said.—AFP