Two junior officials of the Indian High Commission in Islamabad went missing on Monday morning, sources said.
The two personnel went out of the high commission in a vehicle for official duty but did not reach their destination, they said.
They are missing for over two hours, the sources said.
There is no official word on it yet.
The Indian Embassy has taken up the issue with Pakistani authorities.
The incident comes days after India expelled two Pakistan High Commission officials here on charges of espionage.
On May 31, two officials of the Pakistan High Commission were apprehended by law enforcement officials for their alleged involvement in espionage and have been asked to leave the country within 24 hours.
"The government has declared both these officials persona non grata for indulging in activities incompatible with their status as members of a diplomatic mission and asked them to leave the country within twenty-four hours," a statement from the Ministry of External Affairs stated.
According to sources, the two persons have been identified as Abid Hussain and Tahir Khan. While Abid is a resident of Sheikhpura in Punjab, Tahir is a resident of Islamabad.
The duo were apprehended in a joint operation by the Delhi Police and Military Intelligence and were handed over to the MEA. A third Pakistani, a driver with the mission, was also detained during the operation.
Pakistan's Charge de Affaires was issued a demarche and a strong protest was lodged against the two officials whose activities were against India's national security.
"The Pakistan Charge de Affaires was asked to ensure that no member of its diplomatic mission should indulge in activities inimical to India or behave in a manner incompatible with their diplomatic status," the statement added.
Pakistan on the next day summoned a senior Indian diplomat to register strong protest over New Delhi's actions.
Pakistan's Foreign Office (FO) said the Indian Charge d'Affaires was summoned for a "strong demarche", conveying Pakistan's condemnation of the decision to declare two officials of the Pakistan High Commission in New Delhi persona non grata and rejection of all "baseless" allegations against them.
Pakistan also conveyed that the Indian action was in "clear violation" of the Vienna Convention on Diplomatic Relations and the diplomatic norms.
(With PTI Inputs)