Pakistan has said it will respond “at the time and place of its choosing” after its nuclear-arms neighbour India launched a pre-dawn air strike, which they say was targeting militants.

New Delhi said the strikes targeted a terrorist training camp across the Line of Control (LoC), the de facto border between India and Pakistan in the disputed Kashmir region.

The strikes have escalated tensions sharply on the Asian subcontinent with Pakistan’s Prime Minister Imran Khan promising to retaliate in a significant escalation of hostilities between the powers.

“India has committed uncalled for aggression to which Pakistan shall respond at the time and place of its choosing,” Mr Khan’s office said in a statement.

Pakistan denied India’s claim that the attack had inflicted major damage and casualties on militants responsible for a suicide bombing in Kashmir earlier this month as “reckless and fictitious”, and said it would respond in due course.

The attack, if confirmed, would be India’s first use of air strikes against Pakistan since 1971 when the two went to war over Bangladesh’s independence.

Meanwhile Australia has urged both India and Pakistan to “exercise restraint”.

Foreign Affairs Minister Marise Payne said the Australian government was “concerned” about relations between the two nations in the wake of the “horrific” terrorist attack in Jammu and Kashmir on February 14, which Australia condemned.

She urged Pakistan to take “urgent and meaningful action” against terrorist groups in its territory, including Jaish-e-Mohammed which has claimed responsibility for the February 14 bombing, and Lashkar-e-Taiba.

“Pakistan must do everything possible to implement its own proscription of Jaish-e-Mohammed,” Minister Payne said in a statement.

“It can no longer allow extremist groups the legal and physical space to operate from its territory.

“These steps would make a substantial contribution to easing tensions and resolving the underlying causes of conflict.

“Australia urges both sides to exercise restraint, avoid any action which would endanger peace and security in the region and engage in dialogue to ensure that these issues are resolved peacefully.”

The escalation has triggered international alarm, with China and the European Union also calling for both sides to show restraint.

The air strike followed a suicide bombing in India’s section of the disputed territory of Kashmir on February 14 that killed more than 40 Indian soldiers. Pakistan has denied involvement in that attack but vowed to respond to any Indian military operation against it.

It was the worst attack on Indian forces since the beginning of an insurgency in the region in the late 1980s, according to analysts.

Several reporters, including an Associated Press journalist, trudged up the Kangaran Nallah hill to the site of Tuesday’s bombing near the town of Balakot, close to the border with Pakistan’s sector of Kashmir.

Earlier, Pakistan’s military accused India’s air force of violating its airspace, scrambling jets in response.

New Delhi said its jets had hit a JeM training camp and killed “a very large number” of militants training to stage suicide attacks in India.

“In the face of imminent danger, a pre-emptive strike became absolutely necessary,” Indian Foreign Secretary Vijay Gokhale said.

India’s targets were in the region of Khyber Pakhtunkhwa, a significant distance over the Line of Control demarking the two nations’ influence over the contested area.

An Indian government minister confirmed the attacks.

“Air force carried out aerial strike early morning today at terror camps across the LoC (Line of Control) and Completely destroyed it,” minister of state for agriculture Gajendra Singh Shekhawat said on Twitter.

Indian Prime Minister Narendra Modi and his Pakistan counterpart Khan both summoned emergency meetings of top ministers after the attack.

Khan also convened a meeting of the National Command Authority, which oversees command and control of the country’s nuclear arsenal, the military said.

Modi, who is expected to call an election in April, had threatened a “jawbreaking” response to the February 14 attack.

But at a rally on Tuesday, the Indian leader did not directly mention the strike. He paid tribute to the military and said: “I assure the nation that the country is in safe hands.”

“They say they want India to bleed with a 1000 cuts. We say that each time you attack us, be certain we will get back at you, harder and stronger,” said foreign affairs minister of state, Vijay Kumar Singh, a former head of the Indian army.

This is the biggest crisis between the neighbours since 2016, when Pakistan-based militants attacked an Indian army camp in Kashmir, killing 19 soldiers.

Reports suggest up to 12 Mirage 2000 fighter jets crossed the disputed border between India and Pakistan, which embraces the disputed regions of Kashmir and Jammu, about 3.30am local time.

India Today reports the combat jets targeted terror camps and launch pads around Balakot, Muzafarrabad and Chakoti, dropping 1000kg bombs in an operation lasting 20 minutes.

Pakistan’s initial response to the raid was to dismiss its significance, stating India’s bombs fell on nothing of importance.

If reports of the use of the Mirage 2000 jet fighter are correct, it raises a risky aspect to the raid. The jet is capable of deploying nuclear weapons.

Any border crossing by these Indian warplanes could be construed by Pakistan as a nuclear first strike.

Since the suicide bombing in mid February, Indian police have been mainly targeting Kashmir’s largest political-religious group, Jama’at-e-Islami.

The group is dedicated to the right to self-determination for the Himalayan region, which is divided between India and Pakistan but claimed by both in its entirety.

Residents fear the crackdown could be a prelude to a military strike by India against Pakistan or tinkering with Kashmir’s special status in India’s constitution.