Washington CNN  — 

A long-standing rift between Treasury Secretary Steven Mnuchin and the President’s nationalist trade adviser Peter Navarro hit new levels on the sidelines of trade talks in Beijing earlier this month.

Navarro fought with Mnuchin during their trip to Beijing, shouting and cursing at the treasury secretary over his approach to the trade talks with their Chinese counterparts, two sources familiar with the incident told CNN. Navarro, who is the voice of protectionist trade policies inside the Trump administration, grew frustrated with the direction Mnuchin was taking at the talks and was upset that other officials were getting shut out of meetings with the Chinese in favor of Mnuchin engaging in one-on-one talks with China’s Vice Premier Liu He, the sources said.

The argument took place outside the government building in Beijing where the talks were taking place and out of the view of Chinese officials, one source familiar with the incident told CNN.

The blowup was first reported by Axios and comes on the eve of Liu’s visit to Washington on Thursday for the next round of trade talks with his US counterparts.

The White House did not list Navarro, National Economic Council Director Larry Kudlow or Everett Eissenstat, the NEC’s deputy director for international economics, on the list of principal participants for the talks. A senior White House official and a source familiar with the matter said Navarro is not currently expected to take part in the talks. But another senior White House official said that while the three men won’t be part of the official delegation, they will participate in the negotiations.

Navarro and Mnuchin’s Beijing feud came as Navarro grew frustrated when additional one-on-one meetings between Mnuchin and Liu were added to the schedule – leaving other members of the delegation waiting in a hold room, one source said. An administration official confirmed Mnuchin and Liu added one-on-one meetings to the schedule during the trip, but said no team meetings were scrapped as a result.

The White House did not respond to a request for comment.

The escalation in Navarro and Mnuchin’s feud comes amid continued disagreements inside the administration over the future of its economic and trade policies. Navarro and Mnuchin previously feuded over other trade actions, such as the steel and aluminum import tariffs Trump ultimately implemented.

Navarro has few allies left in the West Wing, one source noted. Though his chief enemy, Gary Cohn, has left the White House, Navarro has made few allies in the West Wing beyond the President, who often calls for him by saying, “Where is my Peter?”

Despite Navarro’s struggles internally, he has found himself with a bigger seat at the table since earlier this year, when he was promoted to the position of assistant to the President, coming at a time when Trump has dug back into his nationalist trade instincts.

CNN’s Kaitlan Collins, Kevin Liptak and Sarah Westwood contributed to this report.