LinkedIn said that it removed more than 21m fake accounts in the first half of 2019, amid mounting evidence that the business-focused social network has become a battleground for duelling spies.

The Microsoft-owned company's first moderation report, published on Thursday, revealed that 19.5m fake accounts had been automatically tackled at the moment of registration by its AI systems, with a further 2m "restricted" after being created.

It also showed the biggest-ever rise in government requests for LinkedIn users' data, which rose from 247 in the previous reporting period to a record high of 362.

Many of those of those appeared to be "national security" orders from the US government, which US tech firms are allowed to disclose without giving exact numbers. LinkedIn said that of the 1,170 total accounts that US officials sought to tap, between 250 and 499 were swept up in such orders.

Rob Hallman, LinkedIn's vice president of legal affairs for products and privacy, said that the company "carefully reviews each government request before taking any action", and notifies their targets whenever the law allows it.