Google's parent company Alphabet is reportedly looking for construction firms to start work on its new London headquarters in King's Cross district, after it revived the project.

The company is believed to have sent out invitations to real estate developers to pitch in for the construction work, people familiar with the plan told Bloomberg. Google originally got an approval from the local government to build its new UK headquarters in 2013. Filing suggests that the 2.4 acre project would have a swimming pool, a roof top running track and space for 5,000 employees.

After the tech giant had agreed to buy land from King's Cross Central LP in January 2013, it expected to move into the new premises by 2015. Construction was expected to start by the end of 2013, but the plan was delayed for a more ambitious project.

The company now plans to start construction for the new headquarters before the end of 2017.

A few months after the government had approved it project, Google had scrapped the plan to move into to the new building and pushed the plan to 2017. Joe Borrett, head of real estate and construction at Google told the Telegraph, "We have a great plan for the new building, but we want to challenge ourselves to do something even better for Google, Kings Cross and for the local community."

According to the filing, Google had said a "significant proportion of the 5,000-plus staff would be new jobs". The company would also move some of its employees from buildings it leases in Victoria district and near the Tottenham Court Road tube station. The filing suggests about 16 stores would be built on the ground floor of the new building and King Cross Central will. As part of the deal Kings Cross Central will own the shops.

The application for the site was made by Argent (King's Cross). The London-based real estate developer is one of the owners of King's Cross Central LP, together with London & Continental Railways and DHL.