Slower growth in China and rising market volatility have boosted the risks to the global economy, the International Monetary Fund warned ahead of the G20 meeting, citing a mix of potential dangers such as depreciating emerging market currencies and tumbling commodity prices.
But the G20 had been seen as unlikely to come up with any concrete new measures to address the spillover from instability in the world's second-largest economy, or to call directly on Beijing to address structural issues such as rising bad debts.
Luxembourg Finance Minister Pierre Gramegna, whose country holds the rotating presidency of the European Union, shrugged off the prospect of U.S. interest rate hikes.
"We cannot live all the time on easy money ... One has to be realistic that at one point in time the curve of interest rates will have to change," he told Reuters.
Read MoreG-20: Likely long on rhetoric, short on detail
Bank of Japan Governor Haruhiko Kuroda said any Fed rate rise would be a positive sign for the global economy, despite the unease in some emerging markets that such moves could cause capital outflows and currency volatility.
"If the U.S. were to raise rates, that would speak to the underlying firmness and growth in the U.S. economy, and that would actually be a plus for the global economy," he said.
One specific idea being examined at the Ankara meetings is a proposal from a group of financial stability experts to adopt a two-stage approach for introducing Total Loss Absorption Capacity (TLAC) buffers for big banks, a G20 source said.
The buffer is a new layer of debt big banks like Goldman Sachs and Deutsche Bank must issue to write down in a crisis and bolster their capital.
The proposal would introduce a buffer of 16 percent of a bank's risk-weighted assets from 2019 and 20 percent from 2022, the source said. The United States had pushed for 20 percent, while some in Europe had been arguing for 16 percent on the grounds that their banks were still recapitalising after the financial crisis.
The draft penciled in that a deal should be ready for the endorsement of G20 leaders at their summit in southern Turkey in November, but some countries were concerned there would not be enough time to reach a final agreement by then.