Two of Britain’s most sought-after architects are at the heart of a multibillion-pound redevelopment of Islam’s holiest city.

Lord Foster of Thames Bank and Zaha Hadid are among an elite group of architects and engineers who will provide ideas for an ambitious and highly sensitive construction project in Mecca.

Part of the redevelopment is thought to include a new building near the Haram mosque that will be capable of holding 3 million pilgrims.

The confidential plans, reported in The Architects’ Journal, are believed to be endorsed by King Abdullah bin Abdul Aziz of Saudi Arabia.

Times Archive, 1875: The Pilgrimage to Mecca

'Pilgrimage to Mecca is so necessary a point of pratice that he who dies without performing it may as well die a Jew or a Christian'

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Each year Mecca bursts at the seams when millions of people pour into the city to perform haj, the pilgrimage all Muslims are obliged to carry out at least once in their life. The overcrowding has had fatal consequences: in 2006 more than 300 pilgrims died after a stampede.

Modern Mecca, with its branches of Top Shop and Starbucks, is all but unrecognisable from the city that predated the foundation of the Saudi kingdom

in 1932. Conservationists claim that hundreds of historic buildings have been levelled to make way for high-rise hotels and apartment blocks.

A report by the Saudi British Bank, one of the kingdom’s biggest lenders, estimated earlier this year that £15 billion will be invested by foreign and Saudi companies in construction and infrastructure in Mecca by 2012. Homes and hills are to be flattened and in their place about 130 skyscrapers are planned, including the Abraj Al Bait Towers, which is to be one of the world’s biggest buildings.

At the centre of the development will be the redesign of the mosque and its surrounding area. King Abdullah is understood to have recruited 18 leading architects, engineers and construction firms to “establish a new architectural vision” for the 356,800 square metre complex.

According to The Architects’ Journal the project is likely to be phased, with the initial stage increasing the capacity of the mosque from 900,000 to 1.5 million. Once the scheme is completed capacity for the district should be 3 million.

The proposals have been split into two. Foster & Partners, which is headed by Lord Foster, is one of ten practices that will look at a range of alternatives for the northern expansion of the Haram mosque. Ms Hadid has been given the key job of coming up with ideas for the mosque itself, as well as “revisiting the whole area of the central district”.

A source close to the project told The Architects’ Journal: “The main objective of the design studies is to enrich our discourse on how we should address the future architecture of the Haram.”

Lord Foster, 73, and Ms Hadid, 58, are both former winners of the Pritzker Prize, architecture’s equivalent of a Nobel prize.Lord Foster’s masterpieces include “the Gherkin” in London and Beijing airport. Ms Hadid is working on the Aquatic Centre for the London Olympics.

Neither would comment on the plans.

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