The delegation of eight members of Bolsonaro's ultraconservative Social Liberal Party (PSL) said it was on the visit to check out Chinese facial-recognition technology, with a view to it maybe being used in Brazil to combat crime.

A Brazilian writer regarded as part of Bolsonaro's brain trust, Olavo de Carvalho, slammed the trip as "craziness" and the lawmakers taking part as "hayseeds," "semi-illiterates" and "idiots."

Bolsonaro himself was reported to be "surprised" by the trip.

That fury stemmed from fears that the lawmakers -- who are to take up their seats in Brazil's new congress from next month -- were naively being used by Beijing, and that sensitive data generated by the facial-recognition technology could end up in Chinese hands.

Underlying that was Bolsonaro's scepticism of China, which is Brazil's biggest trading partner and foreign investor.

He has accused China of wanting to "buy Brazil" by taking control of strategic companies, raising friction with Beijing but alarming his economic team.

There is also the fact that China is governed by its Communist Party -- and that Bolsonaro is ferociously opposed to all leftwing ideology.

In a video posted on social media on Wednesday, Carvalho -- nicknamed "Bolsonaro's guru" -- ranted against the traveling lawmakers.

"You are handing Brazil over to China.... Are you going to let these guys hand Brazil over the Chinese system in this way?" he said.

A PSL deputy, Daniel Silveira admitted the trip was being paid for by the Chinese government, but stressed the goal was simply a fact-finding mission to learn more about a technology "we want to apply in Brazil."

He added that it was in Brazil's interest to maintain open channels with other countries, even those with different ideologies, such as North Korea where Brazil has a diplomatic mission, so it can seek to "improve" those countries.

Another PSL deputy, Soraya Thronicke, tweeted: "Who is going to bear China withdrawing from the (Brazilian) market? The 'hayseeds' here have a lot to learn from them (the Chinese)."

A PSL colleague, Carla Zambelli, was quoted in Brazilian media saying that the brouhaha was due to a "big communication error" and that, in any case, the lawmakers were not qualified to sign any technology deal with China.