LONDON: Britain is not aware of any impact from the hacking of U.S. departments believed by U.S. sources to have been carried out by Russia, a spokesman for Prime Minister Boris Johnson said on Monday, adding that investigations were taking place.

Hackers believed to be working for Russia have been monitoring internal email traffic at the U.S. Treasury and Commerce departments, according to people familiar with the matter.

"Investigations are ongoing. The National Cyber Security Centre is working to assess any UK impact, but we're not aware of any UK-related impact at this time," the spokesman told reporters.