Pakistan and India on Friday exchanged lists of their nuclear sites under an annual accord, after a year of strained relations between the arch-rivals, Pakistan's foreign ministry said.

The New Year's Day exchange is aimed at protecting the sites in case of war and was established under a 1988 agreement on the prohibition of attacks on each other's nuclear installations.

"The governments of Pakistan and India today exchanged lists of their respective nuclear installations and facilities," a ministry statement said.

It added that the lists were handed over to officers of the Pakistani and Indian high commissions in New Delhi and Islamabad.

Relations between the two nuclear-armed rivals worsened dramatically after attacks in India's financial capital Mumbai in November 2008, which New Delhi blamed on the banned Pakistani militant group Lashkar-e-Taiba (LeT).

Under the 1988 agreement, both nations are to refrain from attacking nuclear facilities in the event of war. The neighbours have also set up a telephone hotline to prevent accidental nuclear conflict.

India and Pakistan have fought three wars, two of them over the Himalayan region of Kashmir, which is divided between them but claimed by both.

The two countries came close to another war in 2002 after an attack on the Indian parliament that New Delhi also blamed on LeT.

But after deploying hundreds of thousands of troops to the border, Islamabad and New Delhi retreated following intense international mediation.

In 2004 they launched a peace process, but that is now on hold following the Mumbai attacks, with New Delhi pressuring Islamabad to do more to punish those responsible for the carnage and to crack down on anti-India groups.