US President Joe Biden says the leaders of the Group of Seven nations reaffirmed a "shared and unwavering commitment" to support Ukraine against the continuing Russian invasion.

Biden was speaking to reporters after the close of the G7 summit in Hiroshima.

Biden said the G7 countries will continue to "stand with the brave people of Ukraine as they defend themselves against Russia's brutal war of aggression and war crimes."

He stressed that the United States will launch new efforts with partners to train Ukrainian pilots on fourth-generation fighter aircraft, including the F-16, to strengthen Ukraine's air force as part of a long-term commitment to the country's ability to defend itself.

Biden also touched on the G7's approach to China.

He said, "We're not looking to decouple from China. We're looking to de-risk and diversify our relationship with China."

He said G7 countries would take steps to diversify their supply chains so that they are not dependent on one country, and resist economic coercion together.

He also expressed hope for a thaw shortly in his country's frosty relations with Beijing.

Referring to his visit to the Hiroshima Peace Memorial Museum, Biden vowed never to cease efforts to build peace, and continue to work to achieve a world without the threat of nuclear weapons.