ISLAMABAD, PAKISTAN, DEC. 26 -- Three car bombs exploded in crowded markets today, killing at least one man, and Pakistan blamed agents of the Soviet-backed government in neighboring Afghanistan.

Witnesses and doctors said the bombs, which exploded in two markets on the eve of the eighth anniversary of Soviet military intervention in Afghanistan, killed a shopkeeper and injured about 35 people, three seriously.

Pakistani Interior Minister Malik Nasim Ahmad Aheer told reporters the blasts, including the first ever in the heart of Islamabad, were a "planned act of foreign terrorism."

"Agents of the Kabul government have come out with a new wave of terrorism to exert pressure on Pakistan to change its just stand on the question of Afghanistan," he said. He added that Pakistan, which hosts about 3 million Afghan refugees and most of the western-backed guerrilla groups fighting the Kabul government, would "never yield to blackmail and would face the situation courageously."

The Pakistani authorities have blamed the Afghan government for a series of blasts that have killed more than 200 people this year, most of them in the region near the Afghan border.

The Islamabad bombs went off near dusk only seconds apart. Two exploded inside cars at a central Islamabad market and the third in a car at another market about two miles away.