An Indian army soldier keeps guard from a bunker near the border with Pakistan in Abdullian, southwest of Jammu, Sept. 30, 2016. Reuters

India was working to secure the release Friday of an Indian soldier captured by Pakistani troops during clashes between the two nuclear-armed nations over the disputed border region of Kashmir. Indian and Pakistani militaries were reportedly in talks for the soldier's release.

“All attempts are being made. The government will take up the matter with Islamabad for his early release,” Rajnath Singh, India’s minister of home affairs, told reporters Friday.

Pakistan claimed earlier this week it captured the soldier after he tried to enter Pakistani territory. The arrest came after India launched a strike attack against Pakistan Wednesday to foil a "terrorist attack" in Indian cities, Indian Lieutenant General Ranbir Singh told reporters Thursday.

Pakistan downplayed the incident, saying there had only been an exchange of fire. Pakistan also said it had killed eight Indian soldiers during the clash, which India denied.

"Who is telling the truth? No outsider knows for sure. The region where the fighting occurred is deep in the Himalayas, along the Line of Control that has long split Kashmir between India and Pakistan. Access to the area is restricted on both sides. Officials in both countries are leaking select details to reporters, while announcing almost nothing openly," the Associated Press wrote Friday.

Pakistan's Prime Minister Nawaz Sharif warned any future "unprovoked and naked aggression" from Indian forces would not be taken lightly.

"No external force has the capability or capacity to challenge the sovereignty and territorial integrity of Pakistan," he said.

The United Nations said it was "following this situation with great concern."

India struck Pakistan days after 18 Indian soldiers were killed during an attack at a military base in Uri on Sept. 18. Pakistan said it had nothing to do with the militant attack.

India and Pakistan have fought over Kashmir, a Muslim-majority region, for the past 70 years. Both countries share the region and have fought two wars, in 1947 and 1965, over territorial claims.