Afghan government forces carried out intensive air and artillery bombardments of rebels pressing an offensive against the eastern city of Jalalabad. Guerrilla leaders hope to capture Jalalabad for the seat of their interim government. Afghan planes bombed rebel areas on the outskirts of Jalalabad and in Samarkhel, several miles to the southeast, where rebels captured a government garrison last week. Each side has reported inflicting heavy losses on the other. Thousands of refugees have crossed the border into Pakistan to escape the fighting.