"Competition requires dialogue and diplomacy," Sullivan told a small group of reporters on Friday in reference to China while discussing AUKUS.

"We encourage the PRC (People's Republic of China) to have regularised patterns of communications at senior levels," Sullivan said.

Biden said in mid-February he expected to speak to Xi about what the United States said was a Chinese spy balloon that flew through American airspace, worsening already tense relations.

No such call has yet been announced and when asked when it would happen, Sullivan replied: "When the People's Congress is over and the government, including the president, return to work in Beijing the (US) president anticipates the opportunity to engage in a phone call."

"Over the course of 18 months we have communicated with (China) about AUKUS and sought more information from them about their intentions," Sullivan said, referring to China's military buildup, including nuclear powered submarines.

Xi plans to speak with Ukrainian president Volodymyr Zelensky for the first time since Russia's invasion of Ukraine, the Wall Street Journal reported on Monday. That call was likely to take place after Xi's visit to Moscow next week to meet with Russian president Vladimir Putin, the report said.

The US's Sullivan told reporters en route to San Diego on Monday that Washington has been publicly and privately encouraging Xi to talk to Zelensky so that they hear "not just the Russian perspective" on the war.

Sullivan added that Ukraine had not confirmed a call between Xi and Zelensky.