Akbar Al Baker voiced his support for the construction of a third runway at London's Heathrow hub and said Britain could not afford to wait the 20 years it would take to build a new four-runway hub airport in the Thames Estuary - a project supported by London Mayor Boris Johnson.

"Heathrow is bursting at the seams and has already reached a critical point," said Al Baker in a speech in London on Wednesday.

"Already heading towards a double dip recession, the UK cannot afford to lose out on the huge benefits a third runway would bring to the economy in south east England and the country as a whole through the creation of more jobs and more business opportunities."

London's Heathrow hub - the capital's busiest airport - is operating close to full capacity after Britain's Conservative-led coalition government blocked development of a third runway when it came to power in 2010, as further expansion of the west London site would mean a huge increase in the number of planes flying directly over the capital.

A commission chaired by former Financial Services Authority head Howard Davies to analyse ways to expand airport capacity in southeast England will report in the summer of 2015 after releasing an interim report next year.

Al Baker said the third runway debate "was not an option, but a necessity" and that no increase in capacity would lead to further economic hardship and job losses.

"Measures to expand need to be taken soon to avoid a catastrophic situation in the future. The UK government cannot afford to immerse itself in long-winded debate and public enquiries. Action needs to be taken," said Al Baker. "Heathrow is already losing out to European neighbouring hubs that have the resource to expand capacity."

Ferrovial's (FER.MC) BAA has seen traffic between Heathrow and emerging markets rise in recent years and believes it is now falling behind rival European airports in Frankfurt, Paris and Amsterdam in the battle for these lucrative routes because of constraints on growth.

Earlier on Wednesday, London's Gatwick airport said it was studying options to build a second runway and intends to submit the findings to a British government under pressure to resolve the country's air capacity crisis.

Qatar Airways last week became the first major Gulf airline to announce plans to join the oneworld alliance. Members of the alliance, which includes American Airlines (AAMRQ.PK), British Airways (ICAG.L) and Cathay Pacific (0293.HK), cooperate in areas such as route networks, frequent flyer schemes and parts procurement.

(Reporting by Rhys Jones; Editing by Marguerita Choy)

• A Permanent Economic Emergency