Islamabad, May 18 (IANS): Two staffers at the Pakistan Embassy in Kabul were detained by the National Directorate of Security (NDS), the intelligence agency of Afghanistan, under unclear circumstances, the media reported on Thursday.

The two men, Hassan Khanzada and Syed Munir Shah, were at a market when they were picked up by NDS members and taken to one of their detention centres along with the embassy's official vehicle, Dawn online reported.

Khanzada serves as a visa assistant at the embassy, and Syed Munir Shah is a staff driver.

The embassy approached the Afghan Foreign Ministry and sought immediate release of the two staffers.

Khanzada and Shah were finally released after three hours, reports Dawn online.

On Wednesday, Afghan deputy head of mission Zardasht Shams was summoned to the Foreign Office over the detention of the embassy staffers.

"The Afghan deputy head of mission was summoned to the Foreign Office today to lodge Pakistan's strong protest over the incident in which two diplomatic officials in Kabul were detained, reportedly by Afghan security agencies," the Foreign Office said.

Pakistan accused Afghanistan of violating Vienna Convention of Diplomatic Relations (1961).

"It was emphasised that such incidents undermined the constructive engagement which the two countries envisaged for strengthening of bilateral ties," it said.