Three American architects with UK offices are in the running to design the American government’s new US embassy in London. In fact, they are the only UK-based architects eligible for the work.

According to tender documents released by the US State Department last week, only American architects with experience of working on American embassies will be considered in the competition to design the facility, which will be in the Nine Elms area of Wandsworth, west London.

The documents state that both the architect and main contractor must have “defence security service secret facility clearance”, which only American firms are eligible to receive. This means UK contractors and architects are effectively banned from tendering.

HOK designed an embassy for the State Department in Tanzania, KPF has worked in Cyprus and SOM won the Chinese embassy in Beijing.

The State Department announced in September that it intended to sell its Mayfair embassy in Grosvenor Square.

Robert Tuttle, the US ambassador, said the new embassy would be “secure and environmentally sustainable … I’m excited about America playing a role in the regeneration of the South Bank.”