By Harry Robertson and Yoruk Bahceli

LONDON Global regulators and bond traders were on Friday trying to gauge the impact of a ransomware attack on the Industrial and Commercial Bank of China (ICBC), China's biggest bank, that disrupted trades in the vital U.S. Treasuries market this week.

ICBC's U.S. arm was hit on Thursday in the latest of a string of ransomware attacks this year that have targeted companies around the world.

China's foreign ministry said on Friday that ICBC was trying to minimise the risk impact and losses after the attack, which a number of experts attributed to hacking group Lockbit.

Meanwhile, Britain's Financial Conduct Authority said it was "communicating with the relevant U.S. and UK authorities and firms to identify any impacts to UK financial services".

China's foreign ministry spokesperson Wang Wenbin said that business remained normal at ICBC head office, other branches and subsidiaries across the globe.

"ICBC has been closely monitoring the matter and has done its best in emergency response and supervisory communication," Wang told a regular news conference.

Some market participants said trades going through ICBC were not settled due to the incident and that market liquidity had been affected. It was not clear whether this contributed to the weak outcome of a 30-year bond auction on Thursday.

Traders and portfolio managers in Europe on Friday said bond markets appeared to be functioning normally.

"Some illiquidity can be blamed on the U.S. Treasury inter dealer broker market around the time of the hack and post-auction," said one fixed income manager at an asset management firm in Europe.

But the investor said market moves were hard to disentangle from a bond sell-off after comments from Federal Reserve Chair Jerome Powell and the fallout from the poorly received auction.

ICBC said it had successfully cleared Treasury trades executed on Wednesday and repurchase agreements (repo) financing trades done on Thursday.

Since Lockbit was discovered in 2020, the group has hit 1,700 U.S. organizations, according to the U.S. Cybersecurity and Infrastructure Security Agency.

While market sources said on Thursday the impact of the ICBC hack appeared limited, the attack underlined how vulnerable systems at large organizations continue to be.

The yield on the 10-year U.S. Treasury note, which sets the tone for borrowing costs around the world, was last down 3 basis points at around 4.59%. It rose 11 basis points on Thursday, with yields moving inversely to prices.

ICBC's Hong Kong-listed shares ended Friday down 0.8% compared to a 1.13% drop in a Hong Kong index of mainland Chinese banks. Its Shanghai-listed shares closed flat.

(Reporting by Harry Robertson in London, Yoruk Bahceli in Amsterdam; Editing by Dhara Ranasinghe and Alexander Smith)