The Indian government said Sunday that the two had been detained for "indulging in espionage activities", and given 24 hours to leave the country.

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.

India media said the two officials -- both working in the embassy visa department -- had been detained Sunday while trying to obtain information on an Indian security establishment.

The pair returned to Pakistan via the Wagah border crossing, which has been closed for several weeks because of the coronavirus lockdown, a Pakistan embassy spokesman told AFP.

Pakistan summoned India's charge d'affaires to express its "condemnation" of the expulsion order.

The foreign ministry called the allegations "baseless" and said Delhi's action was a "clear violation" of the Vienna Convention on diplomatic relations.

Kashmir has become a bigger source of tension between the two powers since India last August scrapped the Muslim-majority region's semi-autonomous status and imposed a major security clampdown.

In response, Pakistan recalled its ambassador from Delhi and sent back the Indian envoy.

India and Pakistan have fought two of their three wars since independence over Kashmir.

Shelling across their Kashmir demarcation line is a near-daily occurrence, and in February 2019 they conducted tit-for-tat airstrikes.

Rebel groups in Indian-administered Kashmir have battled for decades for the region's independence or its merger with Pakistan.

Since 1989 the fighting has left tens of thousands dead, mostly civilians.

India has more than 500,000 troops in Kashmir, where clashes are a common occurrence but last month extended into the regional capital Srinagar.

New Delhi regularly accuses arch-rival Pakistan of arming and sending rebels across the heavily militarised border. Islamabad denies the claims.