Technology Crime Suppression commander Pisit Paoin says Tuesday that police want to review the data of users they suspect are involved in crimes including posting statements against the Thai monarchy, arms trading, prostitution and drug dealing.
Thailand has draconian lese majeste laws and tries to scrub the Internet of statements critical of the king and his family.
Pisit says his unit approached app operator Naver in South Korea, and in Japan where its servers are based, and is hopeful of cooperation.
Line has more than 10 million users in Thailand.
Last week, police questioned four people for posting coup rumors on Facebook and threatened to charge anyone who "liked" the postings.
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