Mujahideen rebels, using tanks and other armor against Afghan troops for the first time, have launched a fresh assault on the eastern city of Jalalabad, the Afghan government said Saturday.

The attack on the city, earmarked by the rebels as seat of a provisional government proclaimed last month, began Thursday but government aircraft drove off the attackers, Kabul said.Government spokesman Moham-mad Nabi Amani also reported an attack Friday by 2,500 Moslem reb-els on the city of Kandahar, 300 miles to the southwest, describing it as the most serious assault on the city to date.

Civilian reports from Jalalabad, which like Kandahar is near the border with Pakistan, said a food shortage was becoming desperate, but the government spokesman said supply convoys arrived in the city on three successive days up to Saturday.