Industrial and Commercial Bank of China (ICBC) has been unable to convince some market participants that it is safe to reconnect their computer networks to the bank's U.S. unit after a ransomware attack disrupted its systems, Bloomberg News reported on Wednesday.

The attack impeded trading in the $26 billion Treasury market and has left users of the bank's U.S. arm skittish about trading with the bank, the report said, citing people familiar with the matter.

ICBC did not immediately respond to Reuters' request for a comment.

ICBC's U.S. arm was hit by a ransomware attack earlier this month. The breach, claimed by cybercrime gang Lockbit, was so extensive even the corporate email stopped working and forced employees to switch to Google mail.

The blackout left the brokerage temporarily owing BNY Mellon $9 billion, an amount many times larger than its net capital, a measure of resources at hand to promptly satisfy claims.

(Reporting by Pritam Biswas in Bengaluru; Editing by Shilpi Majumdar)