NEW DELHI -Troops from Pakistan and India exchanged fire in disputed Kashmir for a third night in a row, officials said Sunday, as relations between the nuclear-armed rivals plunged to their lowest level in years.

An attack on tourists in India's Himalayan territory of Kashmir this week sparked a new crisis between nuclear armed South Asian neighbours India and Pakistan, with New Delhi blaming militants with "cross-border linkages" for the killings.

The Indian military says Pakistani soldiers fired at Indian posts all along the highly militarized frontier in disputed Kashmir as tensions flare over attack on tourists.