The two Chinese nationals were taken into police custody from Quetta's Kharotabad area days before their abduction and were informed about the threat to their security, Pakistan's interior ministry told the media, days after it said the duo were Christian preachers.
"They were offered security but they refused to accept the offer," the ministry said about the duo who were in Pakistan on business visas, according to Dawn.
Pakistan also said it has canceled the visa of a South Korean national who was allegedly associated with the duo and who was involved in illegal Christian missionary work, reported The Express Tribune.
In addition, Pakistan government sources told Dawn its security and intelligence organisations are checking the background of the two Chinese nationals and analyzing various pictures uploaded on social media to get more details.
China on Wednesday stressed that its citizens must always "observe local laws" when traveling abroad.
The pair, identified as Lee Zing Yang, 24, and Meng Li Si, 26, were abducted on May 24 in Quetta, Balochistan. Last week, ISIS's Amaq propaganda agency claimed its members had killed them.