The United States is seeking to increase the supply of crucial 155mm ammunition to Ukraine to support its counteroffensive.

Officials cited by the newspaper say the United States has already signed agreements with Bulgaria and South Korea to supply shells to Ukraine and is negotiating with Japan on the same.

The Financial Times says that the Biden administration has been aware of Ukraine's  depleted ammunition stockpile for several months and has stepped up efforts to deliver the shells to Kyiv.

According to the publication's sources, US efforts to provide weapons are focused on supplying more 155 mm calibre shells, including supplies from international allies in the short term as well as plans to increase their production in the US over the next two years.

According to the US Army, Washington aims to produce up to 90,000 rounds per month by fiscal year 2025, up from 24,000 now and 14,000 per month before Russia's full-scale invasion of Ukraine.

The United States is therefore building more production lines, including refurbishing a facility in Canada and installing a new assembly line in Texas. Army officials said they may also create new facilities to load, assemble and package 155 mm ammunition in Arkansas, Iowa and Kansas.

Earlier, the United States allocated a military assistance package to Ukraine worth US$800 million. It included cluster munitions for the first time.

The White House has previously explained that the provision of cluster munitions is a temporary measure until the capacity to produce conventional artillery ammunition is deployed. In addition, Ukraine pledged to minimise the risk of using cluster munitions.