Two Indian High Commission staffers in Islamabad went missing on Monday morning following which India has taken up the matter with the Pakistan Foreign Office, government sources said.
The two junior staffers went out of the high commission in a vehicle for official duty at around 8:30 am (IST), but did not reach their destination, they said.
The Indian embassy has taken up the matter with the Pakistan Foreign Office, and sent a preliminary report to New Delhi, the sources said.
The incident comes two weeks after India expelled two Pakistan High Commission officials here on charges of espionage.
India had declared Abid Hussain and Muhammad Tahir as 'persona non grata' after they were found obtaining sensitive documents relating to movement of Indian Army troops from an Indian national, according to authorities in New Delhi.
Following their expulsion, Pakistani agencies started harassing a number of Indian High Commission officials in Islamabad including charge d'affaires Gaurav Ahluwalia.
Ahluwalia's car was aggressively tailed by Pakistani agencies on at least two occasions following which India lodged a strong protest with the Pakistan Foreign Office.
After expulsion of the two Pakistani officials, it was expected that Pakistan would also resort to a tit-for-tat response, going by similar episodes in the past.
India's expulsion of the two Pakistani officials and subsequent harassment of Indian High Commission staffers in Islamabad by Pakistani agencies came in the midst of frayed ties between the two countries over reorganisation of Jammu and Kashmir by India.
Pakistan had downgraded diplomatic ties by expelling the Indian High Commissioner in Islamabad following India's decision to withdraw special status of Jammu and Kashmir in August last year.