A senior Pakistani official says India has accumulated a stockpile of nuclear weapons which threatens to undermine the balance of power in the troubled South Asian region.

Pakistan’s foreign office spokesman, Nafees Zakaria, said during his weekly briefing on Thursday that India has built a “secret nuclear city” where a stockpile of nuclear weapons has been accumulated, Pakistan's English-language newspaper Dawn reported.

The spokesman added that India has been conducting tests on intercontinental missiles, adding that such acts are impacting the existing balance of power in the region.

Zakaria also stressed that the Indian government should reciprocate the steps taken by Pakistan for peace in the region.  

“Pakistan remains committed to the principles of peaceful existence with all of its neighbors, including India,” he said.

Elsewhere in his remarks, the Pakistani official said that India had been "exposed" by the failure of its efforts to isolate Pakistan.

The report in the Pakistani newspaper added that India had technical capacity and sufficient material to build up to 492 nuclear bombs, according to a study published by the Institute of Strategic Studies, Islamabad (ISSI).

Meanwhile, Vikas Swarup, spokesperson of India’s Ministry of External Affairs, on Thursday rejected Pakistan’s claims as baseless.

“Pakistan’s claims of India’s secret nuclear city [are] baseless. This aims to deflect attention from real issue of terrorism,” said the Indian official.

Director General Disarmament at Pakistani Foreign Office Kamran Akhtar has recently demanded that India bring its entire nuclear program under the safeguard laid out by the International Atomic Energy Agency (IAEA).

“There is a fear that the Indian reactors not mandated by the safeguards might be used clandestinely for plutonium production and the existing stockpiles might be diverted to a military program at a subsequent stage,” he said.

In recent years, Pakistan and India have routinely tested ballistic missiles capable of carrying nuclear warheads since they first became nuclear powers in 1998 and 1974 respectively.

Neither of the neighbors has signed the nuclear Non-Proliferation Treaty (NPT) or other international regulatory pacts that restrict developing or testing nuclear weapons.

India and Pakistan say the NPT is discriminatory.