Nvidia has hired one of the largest law firms in the US to investigate the affair between its own chief executive and an alleged Chinese spy.

Jensen Huang, who co-founded the tech company, has admitted to having a romantic relationship outside of his marriage. The woman, Alice Huang, is alleged to be a spy for Beijing.

Nvidia said on Tuesday that it had hired New York law firm Wachtell, Lipton, Rosen & Katz, and that its attorney Joon Kim would lead “a thorough and independent investigation”. The FBI is also conducting its own probe.

The company’s share price has fallen almost to a yearly low, with $500bn (£375bn) wiped of its stock market value since Friday.

Nvidia is widely considered one of the most important companies behind the artificial intelligence (AI) boom given it is the sole manufacturer of a crucial computer chip required for successfully operating AI tools.

It is the world’s second most valuable company after Apple and its chips have become a matter of national security for US officials keen to win the AI race.

Alice Huang was an executive at a Singaporean company Megaspeed, which has been a customer of Nvidia.

The company had been suspected of helping divert Nvidia chips to China, a concern that Nvidia has said was investigated and debunked.

Nvidia has also maintained the US government did not inform the firm that Megaspeed posed an intelligence concern.

According to the New York Times, Secretary of State Marco Rubio sent a memo to top officials in Washington in spring of this year warning that the Jensen Huang was in a close relationship with a Chinese spy.

Beijing has rejected claims that Jensen Huang has been targeted, with its foreign ministry saying the allegations were “intended to smear and malign China”.

US President Donald Trump said Monday that he had spoken to Jensen Huang and that the Nvidia boss told him “I had no idea she was a spy.” Trump said he believed the him.

However, the relationship has drawn more political attention. Congressional leaders of the House Committee on Foreign Affairs have asked Jensen Huang to appear next week for a closed door briefing.

The Nvidia boss has yet to say whether he will attend, a person familiar with the committee’s demand told the BBC.

The committee has the authority to subpoena Jensen Huang, effectively forcing him to appear before the committee, if deemed necessary.

When announcing on Sunday that it would investigate the affair, Nvidia’s board said it had no reason to believe the company’s secrets or national security were compromised.

It added that a committee of independent directors would oversee the probe.