Chinese firm Lenovo insists it is not a state-owned enterprise

Assistant Secretary of State Richard Griffin said the department would also alter its procurement process to ensure US information security was guaranteed.

His comments came after Rep Frank Wolf expressed national security concerns.

The company Lenovo insisted such concerns were unwarranted and said the computers posed no security risk.

Last year, Lenovo - the world's number three PC maker - bought the IBM PC Division and moved its executive headquarters from China to the US.

A Chinese government agency owns 28 percent of Lenovo, while IBM still has about a 13 percent stake in the company.

'Classified network'

In a letter to Mr Wolf, Mr Griffin said government security experts had recommended the computers "be utilised on unclassified systems only".

He said the government was committed to ensuring the purchase would not "compromise our information and communication channels".

And he said the state department would change the way it buys its technology "in light of the changing ownership of IT equipment providers."

His letter did not refer to Mr Wolf's specific concern that at least 900 of the computers were to be used "as part of the classified network deployed in the United States and around the world in embassies and consulates".

Mr Wolf, Republican chairman of the committee that oversees the department's funds, told reporters that China's spying efforts were "frightening".

It was "no secret that the US is a principal target of Chinese intelligence services", he said, adding: "No American government agency should want to purchase from them".

'No security risk'

But Lenovo insisted the state department computers, which were made at former IBM facilities in North Carolina and Mexico, posed no security threat.

"We are absolutely confident in the security of our manufacturing process," Jeff Carlisle, the firm's vice-president of government relations, said.

"These computers do not present a risk to US security."

He said the Chinese Academy of Sciences, an arm of the Chinese government, had a "minority interest" in the company and was not involved in its day-to-day operations.

"We're not a state-owned enterprise," Mr Carlisle added.