NEW DELHI: Indian Prime Minister Manmohan Singh warned Tuesday that there “cannot be business as usual” with Pakistan after last week's deadly flare-up along the border in disputed Kashmir. “It cannot be business as usual” with Pakistan, he told reporters on the sidelines of an army function.

“What has happened is unacceptable,” he added in reference to the killing of two Indian soldiers, one of whom was beheaded.

“Those responsible for this crime will have to be brought to book.”

Singh's comments came a day after commanders of the two armies traded protests over the border exchanges and the chief of India's million-plus military ordered an “aggressive” response to any fresh cross-border firing.

The Indian government has accused Pakistani soldiers of crossing into Indian territory and killing two of its soldiers on Jan 8.

Pakistan denies its troops were involved in any such incident and has accused Indian troops of killing two of its soldiers.

Foreign ministers of both sides have warned against escalating tensions.

But the Indian army chief of staff told his commanders Monday to respond “aggressively” to any future Pakistani firing across the de facto border in Kashmir known as the Line of Control.