The expulsions follow India's decision on Wednesday to expel two high-ranking Pakistani diplomats and two officials at the Pakistan High Commission in New Delhi.
Pakistan ordered the four Indian High Commission employees to leave the country within 48 hours, accusing them of behavior unbecoming of a diplomat, a usual reference to spying.
The men who were expelled were: Vipin Handa, a consular officer; Vakil Ramdas, an attache; R.P. Singh, a second secretary and another official identified only as P. Sundram. High Commissions are the equivalents of embassies between former British colonies.
In announcing its expulsions Wednesday, India claimed, "These officials were indulging in activities incompatible with their official status," in the words of Foreign Ministry spokesman Navtej Sarna.
Like the Pakistani statement, Sarna's remarks implied that they were spying against India.
The expulsions come as the nuclear-armed rivals accused each other of harassing their diplomats in both New Delhi and Islamabad.
India and Pakistan routinely expel one another's diplomats on charges of spying.
The two countries have increased their adversarial rhetoric and missile tests in recent weeks, indicating that despite pulling back from a war stance, neither is in the mood for improved relations.
Sarna repeated charges that India's senior diplomat in Islamabad, Sudhir Vyas, was repeatedly harassed by Pakistani security agents in the past five days.
Pakistani intelligence agents stopped Vyas from leaving his house and used four vehicles to box in his car on Saturday and Monday, he said.
"Such harassment is unprecedented and unacceptable," he said.
Likewise, Pakistan claims Indian security agents harassed its top diplomat in the Indian capital earlier this month.
Its Deputy High Commissioner to India, Jalil Abbas Jillani, complained that Indian intelligence agents followed his car too closely and pursued him into a restaurant, according to newspaper reports. Pakistan protested formally to India on Jan. 7.
India rejected Pakistan's accusation.
India and Pakistan have fought three wars and came to the brink of a fourth in 1998 and again last year, following an attack on India's Parliament that India blamed on Pakistan's spy agency and Pakistan-based militant groups. Pakistan denied the charge.
The two countries' common border was demarcated when the British granted independence to their former colonies in 1947. The dividing line separated Muslim Pakistan from the state of Jammu-Kashmir, which is majority Muslim but claimed by Hindu-majority India. Two of the three India-Pakistan wars have been over Kashmir.
Countries occasionally expel diplomats as a way of registering official displeasure, and the move does not always damage relations.
In 2001, after the arrest of a veteran FBI agent who had slipped secrets to Moscow, the Bush administration expelled several Russian diplomats in an effort to thin the ranks of suspected intelligence officers in the United States. Russia responded by booting several American envoys.
In June 2002, the United States expelled an Iraqi diplomat to the United Nations.