The US government is suing Facebook, alleging the social network discriminated against US workers when hiring foreign employees.

The Department of Justice alleges that Facebook illegally reserved 2,600 jobs for immigrant workers instead of advertising them to workers in the US, according to a lawsuit filed on Thursday.

It is looking for backpay of the workers’ salaries “and other relief to ensure Facebook stops the alleged violations in the future”.  The Department of Justice said the average salary amount of the roles in question was approximately $156,000.

The charges, which are the culmination of a two-year investigation into Facebook’s hiring practices, could have ramifications for British talent in Silicon Valley.

Facebook is accused of reserving positions for immigrant employees with temporary visas, and made it difficult for Americans to apply.

Under US immigration law, non-US citizens are granted visas if their employer can prove that it cannot find a US citizen who could fill their role. The lawsuit alleges that Facebook put multiple barriers in place to stop US citizens from applying for roles it allegedly set aside for foreign workers. This included requiring applicants to apply by post “and refusing to consider US workers who applied for these positions”.

The DoJ claimed that over the two years, Facebook received zero or one US worker applicants for 99.7pc of these positions, while similar positions that were advertised on its careers website during a similar time attracted 100 or more applicants each.

A Facebook spokesman said: “Facebook has been cooperating with the DOJ in its review of this issue and while we dispute the allegations in the complaint, we cannot comment further on pending litigation."

Assistant Attorney General Eric S. Dreiband of the Civil Rights Division said: “Our message to workers is clear: if companies deny employment opportunities by illegally preferring temporary visa holders, the Department of Justice will hold them accountable. Our message to all employers - including those in the technology sector - is clear: you cannot illegally prefer to recruit, consider, or hire temporary visa holders over US workers.”

Silicon Valley has long been one of the largest beneficiaries of skilled foreign workers. A 2018 analysis by the The Centre for Immigration Studies estimated that 71pc of tech employees in Silicon Valley were not born in the US.

The major technology companies that make up the valley have found themselves in a precarious position thanks to crackdowns spearheaded by Donald Trump’s administration.

A visa freeze announced in June drew anger from technology executives like Elon Musk, Jeff Bezos and Sundar Pichai, the Google chief executive who moved to the US from India to study.

Many Britons have found success in the valley thanks to work visas including former deputy Prime Minister Nick Clegg who is now president of global affairs at Facebook and former Moonfruit founder Wendy Tan White who now presides over Google’s X unit.  Apple's former head of design, Sir Jony Ive, was born in London and moved to the US in 1992.