A Soviet-made missile fired from Afghanistan hit a Pakistani border post in "a brazen act of provocation," Pakistan said Saturday, and a Moslem rebel leader said the guerrillas were poised for a new assault on strategic Jalalabad.

A Foreign Ministry statement said the long-range Scud missile hit the border post of Torkham, in the Khyber pass, Thursday. It said the missile, which has a range of 280 miles, caused extensive damage at the base, which is believed to be a training camp for Afghan rebels.