Group of 20 foreign ministers head to a joint summit on Friday that will put some of the staunchest critics of Russia's invasion of Ukraine in the same room as Moscow's top diplomat, in the first such meeting since the war started in February.

The buildup to the gathering on the Indonesian island of Bali has been dominated by the war and its impact on the global economy, with top officials from Europe, the United States and Australia stressing there will be no "business as usual" at the forum, without saying what that might entail.

Russia's invasion has cast a cloud over Indonesia's presidency of the G20 largest economies this year, with speculation of boycotts from some members and a walkout in April at a finance ministers' meeting in Washington.