Poland said Friday it had arrested a Chinese telecoms executive suspected of spying for China, with local media identifying him as a Huawei director.
The arrest comes on the back of a difficult year for Huawei, which has seen the arrest of the daughter of the firm's founder in Canada and US efforts to blacklist the company internationally over security concerns.
The Chinese foreign ministry told AFP it was "highly concerned" by the arrest of its citizen.
Huawei said in a terse statement that it was "aware of the situation" and "looking into it" and had no further comment for now.
The Polish announcement comes weeks after Canada arrested Huawei vice president Meng Wanzhou, who is accused of violating Iran sanctions.
The Chinese telecommunications giant -- which was founded by a former engineer for China's army -- is also facing increased scrutiny over its alleged links to Chinese intelligence services.
Countries like the United States, Australia and Japan have blocked Huawei from building their next-generation, super-fast 5G internet networks.
In December, a Czech cyber-security agency warned against using the software and hardware of Huawei and fellow Chinese company ZTE, saying they posed a threat to state security.
A Polish man "known in the IT sector" was also arrested for alleged espionage along with the Chinese citizen "who is a businessman working for an important telecommunications firm," said Maciej Wasik, deputy head of Poland's special services, quoted by the PAP news agency.
He added that the investigation "had been going on for a while, and had been handled with great care."
The two men were arrested on Tuesday and are suspected of having "worked for Chinese services and to the detriment of Poland," said Polish special services spokesman Stanislaw Zaryn.
According to local media, the Chinese businessman is believed to be one of the directors of the Polish branch of Huawei.
Zaryn identified the Chinese businessman as Weijing W and the Polish suspect as Piotr D.
He said their apartments and workplaces were searched, adding that the Polish suspect had worked "for several state institutions".
Polish media outlets said Piotr D is thought to be a former agent for Poland's ABW counter-intelligence service who is now working as a cyber-security consultant for the Polish branch of French mobile phone provider Orange.
Orange Polska spokesman Wojciech Jabczynski said "ABW officials carried out items belonging to one of our employees on Tuesday."
"We have no information as to whether this is at all related to his work duties," Jabczynski told AFP.
The arrest comes just over a month after Canada detained Meng on a US extradition request.
Meng's December 1 arrest infuriated China, which warned Canada of "serious consequences". Chinese authorities then detained two Canadians -– a former diplomat and a business consultant –- on suspicion of endangering national security.
Britain's largest mobile provider BT said last month that it would remove Huawei equipment from its cellular network after the foreign intelligence service called the company a security risk.
Australia and New Zealand have also enacted similar bans, leaving Canada the only country in the "Five Eyes" intelligence network not to take steps against the Chinese firm.
Meng is the daughter of Huawei founder Ren Zhengfei. Her arrest has sparked a surge of patriotism in China with companies encouraging staff to buy Huawei smartphones, with several companies offering employee subsidies to buy phones from the home-grown company.