LINE, the messaging app popular in Asia, censors politically sensitive keywords on its accounts on phones registered in mainland China, according to research by the University of Toronto’s Citizen Lab.

Released in June 2011, LINE recently reached 300 million users globally, and has the largest messaging app market share in Japan, Thailand and Taiwan. The company launched a Chinese version of its app called Lianwo in partnership with Chinese software firm Qihoo in December 2012.

A company representative told South China Morning Post that Lianwo is “optimised for its local environment… in accordance with local standards and regulations”. It denied censorship was being conducted on its global service.

Citizen Lab, which was set up to research internet censorship, also found that chat traffic from LINE sent over 3G networks was unencrypted in the Android version of the app as late as 20 August 2013. This could potentially mean third parties could listen into private conversations. However, traffic is encrypted over Wi-Fi.

The Thai government said in August it would conduct surveillance on LINE conversations to “ensure the rule of law, order and national security”.

However, LINE told Citizen Lab that its guidelines “focus on user privacy and that’s the company’s priority” and that it hasn’t received an official request from the Thai government to monitor the messaging app.