Flagship phones sold in Europe by China's smartphone giant Xiaomi have a built-in ability to detect and censor terms such as "Free Tibet", "Long live Taiwan independence" or "democracy movement", Lithuania's state-run cybersecurity body said on Tuesday.

The capability in Xiaomi's Mi 10T 5G phone software had been turned off for the "European Union region", but can be turned on remotely at any time, the Defence Ministry's National Cyber Security Centre said in the report.

"Our recommendation is to not buy new Chinese phones, and to get rid of those already purchased as fast as reasonably possible", Defence Deputy Minister Margiris Abukevicius told reporters in introducing the report.

Relations between Lithuania and China have soured recently. China demanded last month that Lithuania withdraw its ambassador in Beijing and said it would recall its envoy to Vilnius after Taiwan announced that its mission in Lithuania would be called the Taiwanese Representative Office.

Taiwanese missions in Europe and the United States use the name of the city Taipei, avoiding a reference to the island itself, which China claims as its own territory.

The National Cyber Centre's report said the Xiaomi phone was sending encrypted phone usage data to a server in Singapore. A security flaw was also found in the P40 5G phone by China's Huawei but none was found in the phone of another Chinese maker, OnePlus, it said.

Huawei's representative in the Baltics insist that its phones do not send user's data externally.

The report said the list of terms which could be censored by the Xiaomi phone's system apps, including the default internet browser, currently includes 449 terms in Chinese and is continuously updated.

"This is important not only to Lithuania but to all countries which use Xiaomi equipment", the Centre said in the report.