China's Foreign Minister Wang Yi said the "road to the San Francisco summit will not be a smooth one", the foreign ministry said on Sunday, in a reference to an expected meeting between President Xi Jinping and U.S. President Joe Biden.

Wang met Biden and his top aides in Washington in recent days, agreeing to work together toward the expected bilateral meeting on the sidelines of an Asia-Pacific Economic Cooperation forum summit.

A flurry of bilateral diplomatic engagements in recent months, largely at U.S. request, has aimed at salvaging what were rapidly deteriorating ties early in the year following the U.S. downing of an alleged Chinese spy balloon.

But in remarks on Saturday, Wang cautioned the road to the summit would not be a smooth one and travelling there would not be on "autopilot", the ministry said in a statement.

He was speaking after a discussion with members of the U.S. strategic community in Washington, the ministry said.

Last month, China's top security agency suggested any Xi-Biden meeting in San Francisco hinged on the U.S. "showing sufficient sincerity".

Wang said China and the U.S. needed to "return to Bali", referring to the last meeting between Biden and Xi, on the sidelines of a Group of 20 summit on the Indonesian resort island last November, where they discussed Taiwan, competition and communication.

Washington and Beijing must put into practice the consensus achieved then, "remove interference, overcome obstacles, enhance consensus and gather outcomes", Wang said.

He said both sides have jointly sent out positive signals to stabilise and improve relations, believing it is useful and necessary to maintain dialogue even as there are still various differences and contradictions, and issues to be resolved.

Saturday's discussions also included in-depth exchanges on the interaction between China and U.S. militaries, finance, science and technology, China's investment environment and market access, as well as the Middle East and Ukraine crises.