US President Donald Trump has ousted HR McMaster as his national security adviser and will appoint John Bolton in his place, US media reported on Thursday.

McMaster, who had never met Trump before being interviewed for the role, clashed with the president over the Iran nuclear deal and Afghanistan policy, the Telegraph said in a report.

John Bolton, who served as George W Bush's UN ambassador and reportedly held talks with Trump on Thursday, is known for his hawkish foreign policy views that are more in line with Trump's stances. 

Last month he wrote an article headlined “The Legal Case for Striking North Korea First".

According to the Telegraph, some members of US Congress immediately questioned his selection for the critical position in the White House.

“This is not a wise choice. Mr. Bolton does not have the temperament or judgment to be an effective national security adviser," Democratic Senator Jack Reed said in a statement.  

The report said that one Republican operative, speaking on condition of anonymity, admitted to some concerns about the appointment.

"Some folks think he's a little too hawkish," the source told Agence France-Presse.

"But people who have worked with him think he's a pro and will step into the job knowing the key players, processes and issues."

Trump praised McMaster in his tweet. “I am very thankful for the service of General H.R. McMaster who has done an outstanding job & will always remain my friend,” he said. 

According to the report, McMaster is expected to retire rather than be fired, with reports that the pair had been discussing his departure for weeks.