BAA has conceded that the opening of a second runway at Stansted airport will be delayed by two years due to the downturn causing a sharp drop-off in passenger volumes. The original opening date of the second runway is now being shifted from 2015 to 2017. "We will not be hitting the 35 million in 2015 that we had expected. That is due to the downturn in the economy that is affecting aviation," said a BAA spokesman.

Passenger numbers dropped 6% last year and were flat in 2007 with fewer travellers using Stansted. The slump was exacerbated by Ryanair and easyJet, the airport's largest operators, shifting some services to other London airports.

Anti-expansion campaigners said the postponement proves there is no need for a second runway.

A white paper for the second runway were sanctioned by ministers in 2003, stating that the second landing strip should be launched by 2012. However, that deadline shifted to 2015 in the face of staunch opposition from both locals and environmentalists.

The Conservative party has pledged to block its construction and are exploring legal options to overturn planning permission if it is awarded by the inquiry. It has also urged contractors not to sign any deals to start construction work on the site.

Next week, campaigners from Stop Stansted Expansion group will launch a high court challenge against the government's recent decision to approve BAA's application for an additional 10 million passengers a year at the airport. The group also argues that the latest omission proves there is no need for a second runway.

The proposed Stansted expansion is further complicated by the Competition Commission forcing BAA to sell the Essex airport on monopoly grounds.