The Treasury Department will concentrate on cracking down on those seeking to evade sweeping sanctions imposed on Russia over the war, and those who facilitate such efforts, one of the officials said.

Yellen's decision to avoid some sessions joined by Russian officials underscores the US view that Russia should be excluded from global financial institutions because of its invasion, the official said.

Russian Finance Minister Anton Siluanov may attend at least portions of the G20 meeting virtually, the official said, repeating Yellen's recent comments that it can no longer be "business as usual" for Russia in the G20 and other international institutions.

Yellen will attend the opening G20 finance session on the economic impact of Russia's war in Ukraine, including the IMF's forecast of a 35 percent contraction in Ukraine's economic output this year. Even if Russian officials attend that session, the official said it was important for Yellen to participate in and stand with US allies in support of Ukraine.

Washington and its allies will further pursue consultations on sanctions imposed on Russia, including a focus on thwarting evasion of sanctions previously imposed, one official said.

The official declined to discuss specific next steps, but added that additional sanctions, including measures targeting Russian industries, would seek to further restrict Russia's economy and ability to project power.

Food security crisis

Yellen will convene a high-level panel on Tuesday to discuss the global response to a food security crisis exacerbated by Russia's invasion, the Treasury Department said in a statement.

The meeting will include the heads of the IMF, the World Bank and the International Fund for Agricultural Development, as well as ministers representing the Group of Seven (G7) and G20 members and technical experts from international financial institutions.

US Treasury officials aim to ensure that international financial institutions are sharing knowledge about the key drivers of rising food insecurity, including Russia's invasion of Ukraine, and push them to step up the scale and urgency of their response, a senior Treasury official said.

"Secretary Yellen is deeply concerned about impacts that Russia’s reckless war are having on the global economy, including the risk of rising food insecurity in emerging markets and developing countries around the world," a second senior Treasury official said.

Russia says it is engaged in a "special military operation" in Ukraine.

The crisis was hitting emerging markets and developing countries that were still struggling to recover from the COVID-19 pandemic particularly hard, the official noted.

A third senior Treasury official said the Treasury had no specific aid target in mind for the meeting, noting that officials were still analyzing the extent of the problem.

Yellen is expected to warn against export bans, drawing on lessons from the last big world food crisis in 2008, the official said, while ensuring efforts to boost food production in Africa and other regions highly dependent on imports.

Treasury officials will also call for continued research and innovation to ensure that agricultural production is adapted to climate change factors such as heat and drought.

Yellen first announced plans for the meeting last week, noting that over 275 million people worldwide were facing acute food insecurity. 

Treasury officials expect to release an action plan after the event to help structure the urgently needed global response, one of the officials said.

The World Bank, IMF, United Nations World Food Program and World Trade Organization have also called for urgent, coordinated action on food security, and appealed to countries to avoid banning food or fertilizer exports.

They said the crisis was compounded by a sharp increase in the cost of natural gas, a key ingredient of nitrogenous fertilizer, which could threaten food production in many countries.