Pakistan yesterday summoned a senior Indian diplomat to register a strong protest over India's decision to expel two officials of its High Commission in New Delhi on charges of espionage.

India on Sunday declared two officials of the Pakistan High Commission as "persona non grata" on charges of espionage and ordered them to leave the country within 24 hours, the Ministry of External Affairs said.

The two officials, Abid Hussain and Muhammad Tahir, were caught by Delhi Police while they were obtaining sensitive documents relating to India's security installations from an Indian national in exchange for money, India said.

Pakistan's Foreign Office (FO) said early on Monday that 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, the FO said.

Earlier, Pakistan's Foreign Office said that the two staff members were lifted by the Indian authorities on May 31 on "false and unsubstantiated charges". It said the action was "clearly aimed" at shrinking diplomatic space for the working of the Pakistan High Commission in Delhi.

The officials, working at the visa section of the Pakistan High Commission, confessed during the interrogation that they worked for Pakistani spy agency ISI, official sources in New Delhi said.

Meanwhile, the Pakistan officials returned home to Pakistan yesterday, an embassy spokesman said. The move came amid heightened tensions between the arch-rivals foes over the Himalayan region of Kashmir, which was split between them in 1947 when they gained independence from Britain.