India said on Thursday Pakistan launched an overnight air attack using "drones and missiles", before New Delhi retaliated to destroy an air defence system in Lahore.

"Pakistan attempted to engage a number of military targets ... using drones and missiles," India's defence ministry said in a statement, adding that "these were neutralised" by air defence systems.

New Delhi said that areas targeted included sites in Indian-administered Jammu and Kashmir, and India's Punjab state – including the key cities of Amritsar, Ludhiana, Chandigarh – as well as Bhuj in Gujarat state.

"The debris of these attacks is now being recovered," it added.

The defence ministry said its military had "targeted air defence radars and systems at a number of locations in Pakistan" on Thursday morning, saying that the "response has been in the same domain, with the same intensity, as Pakistan".

It added that it had been "reliably learnt that an air defence system at Lahore has been neutralised".

India also accused Pakistan of having "increased the intensity of its unprovoked firing across the Line of Control using mortars and heavy calibre artillery" across the de facto border in Jammu and Kashmir

India also said the number of people who have been killed by Pakistani firing since the escalation of violence on Wednesday had risen to 16, including three women and five children.

India added that it remained committed to "non-escalation, provided it is respected by the Pakistani military".

The attacks came on the same day that India warned any Pakistan military action would be met with "a very, very firm response".

"Our response was targeted and measured. It [is] not our intention to escalate the situation," Foreign Minister Subrahmanyam Jaishankar said in a speech to his visiting Iranian counterpart.

"However, if there are military attacks on us, there should be no doubt that it will be met with a very, very firm response."

Pakistan Prime Minister Shehbaz Sharif has vowed to retaliate after India launched deadly missile strikes on Wednesday morning, with days of gunfire along their border in Kashmir escalating into artillery shelling.

At least 45 deaths have been reported from both sides of the border following Wednesday's violence, including children.

Pakistan's army said on Thursday it had "so far shot down 25 Israeli-made Harop drones" across the country and that four troops in Lahore were injured.

The Civil Aviation Authority said Karachi airport was closed until 6 pm, or 9 pm Hong Kong time, while Islamabad and Lahore were briefly shut "for operational reasons". (AFP)