Indian men along with their horses cross near the border village of Dallan, in Poonch, 250 kilometers (155 miles) northwest of Jammu, India, Tuesday, Jan. 15, 2013. India's army chief Gen. Bikram Singh on Monday accused Pakistan of planning an attack in which two Indian soldiers were killed in the disputed Kashmir region last week, and warned of possible retaliation. (AP Photo/Channi Anand)

NEW DELHI - Pakistan on Wednesday blamed Indian troops for killing one of its soldiers along the disputed Kashmir border, the latest in a series of tit-for-tat attacks that threaten to ratchet up tensions between the two nuclear-armed neighbours.

In New Delhi, Indian Prime Minister Manmohan Singh said Tuesday that his country's relations with Pakistan "cannot be business as usual." In Islamabad, the Pakistan military claimed Indian troops fired at a Pakistani army post across the so-called Line of Control that divides the Himalayan region.

Two other Pakistani soldiers and two Indian soldiers have died during the past 10 days in the worst bout of fighting in the region in nearly 10 years. India said one of its soldiers was beheaded.

"What has happened is unacceptable," Singh said of the killing of the Indians, according to media reports. He made the brief comments to reporters at a New Delhi gathering for India's annual day honouring the military.

The Pakistani army said the shooting from Indian troops, which started at 10 p.m. Tuesday and lasted for an hour, was unprovoked and occurred in the Hot Spring and Jandot sectors of Pakistan-held Kashmir. The soldier who was killed was identified as Naik Ashraf. The army said he is survived by his wife and three daughters.

The Indian military did not immediately comment on the shooting.

India and Pakistan have been rivals for decades, though ties had been improving markedly in recent years. The two have fought three wars since they were carved out of British India in 1947 — two of them over Kashmir. The region is divided between the two countries, but each claims it in its entirety.

Senior Pakistani and Indian officials so far have kept tension from the recent events from spiralling out of control. They are trying to limit the potential damage to relations, which have slowly warmed since Pakistani militants killed 166 people in the Indian coastal city of Mumbai. They suspended peace talks after the Mumbai attack, but both countries have economic and other reasons for wanting better ties.

Still, the clashes along the Kashmir border highlight how easily simmering tension can flare into conflict. The biggest risk remains an attack by militants like the one in Mumbai that would likely scuttle the reconciliation process once again.

The fighting also comes amid increasing political turmoil in Islamabad, with Pakistan's top court ordering the arrest of the country's prime minister in a corruption case, officials said, and a firebrand cleric rallying thousands of people in the capital against the government.

On Monday, Indian army chief Gen. Bikram Singh accused Pakistan of planning the attacks that left the two Indian soldiers dead — making clear he felt it was not an unintentional skirmish — and warned of possible retaliation.

"The attack on Jan. 8 was premeditated, a pre-planned activity. Such an operation requires planning, detailed reconnaissance," Singh told reporters. He said India reserved the right to retaliate at a "time and place of its choice."

Singh urged his troops to be "aggressive and offensive in the face of provocation and fire" from Pakistan. He said the alleged beheading of the Indian soldier was "unacceptable and unpardonable" and accused Pakistan of violating the "ethics of warfare."

The Kashmir fighting began Jan. 6 when Pakistan accused Indian troops of raiding an army post and killing a soldier. India denied launching the attack and said its troops had fired across the border in response to Pakistani shelling that had destroyed an Indian home.

Two days later, India said that Pakistani soldiers, taking advantage of heavy fog, crossed the de facto border and killed two Indian soldiers, beheading one. On Jan. 10, Pakistan said Indian troops had fired across the border and killed another of its soldiers. The Pakistani army said the shooting was unprovoked, while the Indian military said its troops were responding to fire from across the frontier.

Pakistan and India struck a ceasefire agreement over Kashmir in November 2003. There have been periodic violations of the cease-fire, but the incidents during the past week have been the most serious.

News from © The Associated Press, 2013