President Donald Trump has publicly backed Nvidia chief executive Jensen Huang, saying the chipmaker's boss should stay in his job as the company's board investigates whether he was targeted by a foreign intelligence operation.

Speaking to reporters on Sunday before returning to Washington, Mr Trump called Mr Huang a "fine person" and an "honourable guy" who had "done an amazing job for our country". Asked whether Mr Huang should remain as chief executive of Nvidia, the president replied: "I think so. Oh yeah, sure."

Mr Trump said he had not spoken to Mr Huang about the allegations. "I have not spoken to him about it. I just know he's a fine person, but you never know what is going on," he said. "I hope everything's fine."

He added: "I think he probably has an excuse for it. You have to hear it," and said he had not heard that Mr Huang had done anything wrong. Asked whether he would take the Nvidia chief on his trip to Asia later this month, Mr Trump said: "I don't know, but I'd certainly take him."

The president's remarks came hours after Mr Huang admitted in a message to Nvidia employees on Sunday that he had been unfaithful to his wife and took full responsibility for his actions. Nvidia said on Sunday that its board was launching an independent investigation into reports that its founder and chief executive had been the target of a foreign intelligence effort.

The inquiry will be overseen by a committee of independent directors, assisted by outside legal counsel, and will examine all available information. The board said it had no reason to believe that either United States national security or Nvidia's secrets had been compromised, and it expressed confidence in Mr Huang and his leadership team. Mr Huang will continue as chief executive while the review proceeds, and the company says he is committed to leading Nvidia without interruption.

The controversy centres on reports about Mr Huang's relationship with Alice Huang, a former senior executive at Megaspeed International, a Singapore-based company that buys Nvidia chips. United States intelligence officials believe she was recruited by a Chinese spy agency to gather information about Mr Huang, according to reports in the New York Times and the Financial Times. The two Huangs are not related.

Mr Huang had previously described his contact with her as a normal business relationship. The New York Times reported on Friday that US intelligence officials had told the Trump administration earlier that a woman who had become close to Mr Huang was working for a Chinese spy agency, and that Mr Trump had been briefed on the findings roughly a year ago.

The episode has also drawn in Congress. Three Republican committee chairs in the US House of Representatives have asked Mr Huang to attend a closed-door briefing on 18 November to explain his interactions with Alice Huang and Nvidia's safeguards against foreign espionage.

Mr Trump is one of the technology executives' closest contacts in Washington, frequently consulting Mr Huang on artificial intelligence and China policy. The president has approved Nvidia's push to export some of its older chips to China and has adopted an industry-friendly approach to AI regulation, despite scepticism about the technology from some officials in his administration who want stronger export controls.

Investors will now watch whether the board inquiry, the congressional briefing and the continuing political debate affect Nvidia, the world's leading maker of the advanced chips that power artificial intelligence systems. For now, the company's board, its chief executive and the president are all saying the same thing: Mr Huang stays in charge while the investigation runs its course.