Leaders from the Group of Seven nations agreed new sanctions on Friday that they said would "starve Russia of G7 technology, industrial equipment and services that support its war machine".

The move comes after the United States, Britain and the European Union all announced fresh efforts to turn the screws on Moscow, 15 months into its military campaign in Ukraine.

The bloc, meeting in the Japanese city of Hiroshima, said that they would move to further restrict Russia's access to G7 economies.

"We will broaden our actions to ensure that exports of all items critical to Russia's aggression... are restricted across all our jurisdictions," they said in a statement.

"We will starve Russia of G7 technology, industrial equipment and services that support its war machine," added the bloc, which includes Britain, the US, Japan, Canada, Germany, France, Italy and the European Union.

The grouping said they would step up efforts to prevent circumvention of their existing sanctions regime, "including targeting entities transporting material to the front".

Earlier Friday, Washington and other members announced their own new measures, with a senior US administration official saying another 70 entities from Russia and "other countries" would be placed on a US blacklist.

London took aim at Russia's US$4-5 billion annual trade in diamonds, announcing a ban on the import of the gems, along with copper, aluminium and nickel.

Meanwhile, Ukrainian President Volodymyr Zelensky will attend the G7 summit in person, officials familiar with his plans revealed on Friday.

The surprise trip will be his first to Asia since the war began and would allow him to meet key allies like US President Joe Biden and the leaders of powerful unaligned nations who have been invited, including Brazil and India. (AFP)