US Secretary of State Rex Tillerson could skip a Nato meeting with foreign heads of states on April 5 and 6 and instead attend a meeting at Mar-a-Lago resort in Florida with Donald Trump and Chinese President Xi Jinping. He plans to visit Russia, days later on 12 April, according to a Reuters report.

Tillerson plans to skip a meeting that was supposed to be his first in Brussels with 28 Nato members, four US officials told the news agency.

The decision to visit Russia and miss the meeting in Brussels triggered concerns that the US could be prioritising Russia over Nato allies, two former US officials said.

A US official speaking on the condition of anonymity said: "It feeds this narrative that somehow the Trump administration is playing footsy with Russia."

He added saying, "You don't want to do your early business with the world's great autocrats. You want to start with the great democracies, and NATO is the security instrument of the transatlantic group of great democracies."

State Department spokesperson Mark Toner did not comment on the issue of Tillerson skipping the Nato meeting and visiting Russia.

A former Nato diplomat who spoke to Reuters on the condition of anonymity said he hoped Tillerson could find a way to attend both meetings and that it was important to put up a united front before Russia.

"Given the challenge that Russia poses, not just to the United States but to Europe, it's critical to engage on the basis of a united front if at all possible," the diplomat added.

Trump has repeatedly called the Nato alliance "obsolete" and alleged that Nato members are not paying their fair share. Last week, after a meeting with Chancellor Angela Merkel, Trump claimed that Germany "owed vast sums of money to Nato and Washington".