SRINAGAR, India/LAHORE, Pakistan (Reuters) - Cross-border firing between India and Pakistan killed at least nine people on Friday, the day India marked the 50th anniversary of a war between the two South Asian nations.

On the Pakistani side of the frontier, six civilians were killed and more than 40 were treated for wounds in hospital in the town of Sialkot, the media wing of the Pakistani military said.

India's Border Security Force said three civilians had died and 22 were wounded in firing across the frontier in the northern Jammu region.

Both said the other side had opened fire first.

"Pakistan Rangers resorted to unprovoked firing. Initially, small arms were used but later mortar bombs were shelled on BSF posts and civilian areas," a BSF spokesman said. "The BSF also gave a fitting reply."

Pakistan Rangers spokesman Major Waheed Bukhari gave a different account, saying that unprovoked firing had started overnight from the Indian side. It was followed by retaliation from the Rangers.

A Pakistani military statement also said its troops "are befittingly responding to Indian firing."

The accounts could not be independently verified, but tensions have been running high between the nuclear-armed neighbors since peace talks that were due to be held last weekend were called off at the last minute.

On Thursday, Indian security forces reported the capture of a Pakistani militant in north Kashmir after a shootout in which three other militants were killed. He was the second militant to be taken alive in recent weeks.

The talks had been agreed on at a meeting last month in Russia between prime ministers Narendra Modi of India and Nawaz Sharif of Pakistan, but fell apart over whether the disputed territory of Kashmir should be put on the agenda.

In New Delhi, leaders marked the anniversary of the 1965 war fought over Kashmir that ended in a ceasefire and a return to front lines that predated the conflict. India and Pakistan have fought three wars since independence and partition in 1947.

In a tweet, Modi said: "As we mark the 50th anniversary of 1965 war, I bow to all brave soldiers who fought for our motherland in the war."