Islamabad - Pakistan's foreign office has accused India of harassing and intimidating its diplomats and their families posted in New Delhi, in the latest escalation of tensions between the South Asian neighbours.

In a statement released late on Tuesday, the foreign office said Pakistani officials and their families were facing "intense harassment, intimidation and outright violence from the Indian state agencies".

India said it would investigate the allegations. Indian diplomats posted in Islamabad, the Pakistani capital, alleged to Al Jazeera on Wednesday that they had been facing similar harassment for months.

Pakistan said at least three of its diplomats, and several of their children, had been harassed in recent days.

"This deliberate bullying is not confined to a single isolated event, but continues unabated in a series of incidents, especially targeting the children of our officers and staff," said the Pakistani statement, listing a series of alleged incidents.

On Tuesday, Pakistan alleges that vehicles carrying the children of Pakistani diplomats were stopped and threatened by unidentified men on their way back from school.

The men allegedly took photographs of the children and filmed their exchange with them. This followed similar incidents on March 7 and 8, the statement said.

On March 9, Pakistan alleged that its naval adviser's vehicle was "aggressively chased", while its political counselor was "forcibly evicted from a cab" by unidentified men, who then threatened him.

Pakistan summoned the Indian deputy high commissioner to Pakistan to register a protest at the incidents, the foreign office said.

"Under the Vienna Convention, the safety and the security of Pakistani diplomats and their families is the responsibility of the Indian Government," read the statement.

"The total apathy and failure of the Indian Government to put a halt to these despicable incidents, sparing not even young children, indicates both a lack of capacity to protect foreign diplomats posted in India or a more reprehensible, complicit unwillingness to do so."

Indian allegations

India, however, said that its diplomats posted to Islamabad have been facing similar harassment.

"Cases of harassment and intimidation are normal for Indian diplomats in Islamabad. We have noticed a surge in the last one year," said an Indian foreign ministry official, speaking on condition of anonymity.

The official alleged that members of Pakistan's Inter Services Intelligence (ISI) spy agency entered the Indian residential compound in Islamabad last month, "crossing a red line".

"Aggressive surveillance, violation of physical space and tailing of officers in close and dangerous proximity is a perennial issue," said the official. "[Intelligence agency] personnel keep shooting videos of the officers, thrusting phones on their faces. Obscene phone calls and messages are constantly received on phones."

In one incident, the official said, an Indian diplomat's home was broken into and his laptop stolen.

The South Asian neighbours, which have fought three wars since gaining independence from the British in 1947, regularly trade tit-for-tat allegations of harassment and espionage against diplomats.

In October 2016, Pakistan expelled Indian diplomat Surjeet Singh, saying he had violated the Vienna Convention and "established diplomatic norms".

That followed a day after the detention and expulsion of a Pakistani diplomat by India on similar charges.

Tensions between the nuclear-armed neighbours have been high for months, with India taking Pakistan to the International Court of Justice last year, alleging mistreatment of Kulbhashan Jadhev, an Indian citizen convicted by a Pakistani military court for spying and orchestrating attacks on Pakistani soil.

The two countries regularly exchange fire across the de facto border in the disputed northern region of Kashmir, which both claim in full but administer separate portions of.

The shelling has killed several civilians on either side of the line of control since last year.

There have, however, been minor eases in tensions, too, with Pakistan announcing earlier this month that it had approved an Indian proposal to facilitate an exchange of female civilian prisoners, as well as prisoners who were mentally challenged, had special needs, or were above 70 years of age.

Asad Hashim is Al Jazeera's Web Correspondent in Pakistan. He tweets @AsadHashim