US national security adviser John Bolton said he met at the White House with Hungary's Foreign Minister Peter Szijjarto and discussed "defense cooperation, energy diversity, confronting Russian malign influence and maintaining our ironclad commitment to NATO."

"A great preview of our 2019 goals and Secretary Pompeo's trip next week," Bolton tweeted.

Orban, who extolls Christian values and has fought European Union leaders on welcoming refugees, is one of the few Western leaders who has enthusiastically praised US President Donald Trump.

Pompeo is visiting as Orban faces a wave of street protests that began with a controversial reform of workers' overtime hours which the opposition has called a "slave law."

The Trump administration has shown a willingness to work with Orban, who received a cold shoulder from previous president Barack Obama, but has been annoyed by some recent actions.

The State Department criticized Hungary in November for sending two suspected Russian arm dealers home rather than to the United States to face prosecution.

And the United States voiced disappointment after Hungary's renowned Central European University said late last year it was obliged to move key study programs to Vienna due to tough requirements imposed by Orban on universities it considers foreign.

The university was founded by US-Hungarian billionaire philanthropist George Soros, who is an outspoken proponent of liberal values.

Pompeo will also head on his trip to Poland for a previously announced February 13-14 conference on the Middle East.