Indian Prime Minister Narendra Modi greeted arriving world leaders for Saturday's G20 summit in New Delhi, television broadcasts showed.

Modi shook hands with most arrivals in New Delhi as the Indian capital readies for the two-day discussion of Ukraine, climate change and other contentious global issues.

But with the G20 expected to welcome the African Union into its ranks this weekend, he greeted the grouping's chair and Comoros President Azali Assoumani with a warm embrace.

The expansion of the bloc into the "G21" would be a notable diplomatic victory for Modi, who faces national elections next year and has used hosting rights for this year's forum to burnish his image as an international statesman.

Finding consensus among members has been increasingly difficult in recent years with deep divisions on the Ukraine war.

Russia's Vladimir Putin and China's Xi Jinping have skipped this year's summit altogether.

Moscow continues to press allies to water down international condemnation of its invasion of Ukraine, throwing up a major roadblock to joint action.