Pakistan is 'seriously concerned' by India's recent test of anti-ballistic missiles which can intercept incoming nuclear weapons.

Islamabad: Pakistan is "seriously concerned" by India's recent test of anti-ballistic missiles which media reports say could intercept incoming nuclear weapons, a senior foreign ministry official said on Thursday, warning Pakistan would upgrade its defences.

India's defence and foreign ministries did not respond to requests for comment and the defence ministry has not stated whether any test was conducted. India has not announced these tests in the past.

The row over the missile test is likely to heighten long-running tension between India and Pakistan, nuclear-armed neighbours who have fought three wars since being split amid violence at the end of British colonial rule in 1947.

Both nations have been developing missiles of varying ranges since they conducted nuclear tests in May 1998.

According to media reports, on 15 May, India tested a locally designed Anti-Ballistic Missile system which could in theory intercept a nuclear-carrying ballistic missile.

Islamabad views its nuclear arsenal as a deterrent against India's much larger conventional military.

Sartaj Aziz, foreign affairs adviser to Pakistan's prime minister, told the senate that India's latest test, as well as recent tests of nuclear capable submarine-based ballistic missiles, was "leading to nuclearisation" of the Indian Ocean.

"Pakistan has serious concerns over these developments and will take all necessary measures to augment its defence capabilities," Aziz said.

Pakistan alleges India is building large nuclear-powered submarines capable of carrying nuclear-armed missiles.

Aziz said that India's actions were upsetting the strategic balance in South Asia and affecting the maritime security of other Indian Ocean nations.

"We are not oblivious to our defence needs and will have to upgrade our defensive capabilities through suitable technologies without entering into an arms race," Aziz said, according to a foreign ministry statement.

Indian officials have in the past also voiced concerns about Pakistan's various missile tests.

US President Barack Obama in October urged Pakistan to avoid developments in its nuclear weapons programme that could increase risks and instability.

Washington has been concerned about Pakistan's development of new nuclear weapons systems, including small tactical nuclear weapons, and has been trying to persuade Pakistan to make a unilateral declaration of "restraint."

But Pakistani officials have said Islamabad will not accept limits to its weapons programme and argue that smaller tactical nuclear weapons are needed to deter a sudden attack by India.