By Ann Saphir and David Lawder

SAN FRANCISCO U.S. Treasury Secretary Janet Yellen on Friday said the ransomware attack on the Industrial and Commercial Bank of China that disrupted China's largest bank had not interfered with the market for U.S. government debt.

"We have not seen an impact on the Treasury market," Yellen said, adding that she and China Vice Premier He Lifeng spoke about the issue during talks in San Francisco this week.

The ICBC's access to an electronic settlement platform for U.S. Treasury securities remained suspended on Friday, a day after confirmation of the ransomware attack.

"We have been working very closely with the Chinese, with the firm, and with regulators in the United States, with the federal government, the FBI" and cyber security officials, she said, adding that the incident is an example of why top economic officials in the two countries need to maintain close communications.

"This is a situation where it's critical to be able to pick up the phone and know that you will have a good response on the other end, and that we can trust one another to work together and cooperate," Yellen said at a press conference after wrapping up two days of meetings with her Chinese counterpart. "The Treasury Department and the United States has given "as much assistance as we possibly can to the firm in dealing with this issue," she said.

(Reporting by David Lawder, Ann Saphir; editing by Diane Craft)