A US sanctions agency reportedly has investigated domestic and foreign companies for shipping chips used for military applications to Russia despite restrictions put in place during the war with Ukraine.

Reuters reported the Office of Foreign Assets Control (OFAC), which is the enforcement arm of the US Treasury Department, is spearheading the investigations, but the news agency noted specific names of the companies are not available.

A US official told Reuters senior officials from the Treasury, Commerce and State Departments are contacting US-based microelectronic companies to halt the flow of chips to Russia.

OFAC is also looking into whether US financial companies are being used to enable trades with sanctioned individuals. OFAC is working to halt shipments to Russia by using administrative injunctions and blocking orders, Reuters reported.

The US official told the news agency that experts are working with companies to look at data from more than 600 distributors that appear to be selling restricted parts to Russia.

Bloomberg reported Russia imported more than $1 billion worth of advanced US and European chips last year despite the restrictions.