Britain has announced a further Stg 1.3 billion ($A2.26 billion) in military support and aid to Ukraine, making the pledge ahead of a planned video call on Sunday by Group of Seven leaders with Ukrainian President Volodymyr Zelenskiy. The UK's Prime Minister Boris Johnson has been one of the strongest supporters of Ukraine's efforts to resist Russian forces since President Vladimir Putin launched his invasion on February 24. Johnson's government has sent anti-tank missiles, air defence systems and other weapons to Ukraine.