HERAT (AFP) - An Afghan army helicopter crashed in western Afghanistan Thursday, killing all 13 on board including a top army general in the force's worst such incident since the end of Taliban rule, officials said. The helicopter, carrying a delegation of senior Afghan National Army officers, came down in bad weather in the Adraskan district of Herat province, defence officials said. "The commander of Zafar military corps, General Fazel Ahmad Sayar, together with 12 other ANA members, were on their way from Herat to Farah province when due to bad weather their helicopter crashed," the Defence Ministry said. "All those on board were martyred," it said in a statement. Ministry spokesman Gen Muhammad Zahir Azimi told AFP it was the worst such crash for the fledgling Afghan army since the ouster of the Taliban in late 2001. The delegation had been en route to neighbouring Farah province to visit an army base, defence officials said. The crash site was about 80km south of Herat city. Basir Khan Ghori, spokesman for the 207th Zafar (Success) military corps, said the helicopter had crashed into a mountain in poor weather, and confirmed the Gen's death. "There is very thick cloud cover and fog in the area where the crash took place," Ghori told AFP. "The helicopter hit a mountain peak. All the bodies were burnt." But another Defence Ministry official said on condition of anonymity that it was not clear if the Russian-designed Mi-17 chopper crashed because of the weather or if it was brought down by "enemy fire". Besides the commander, the dead included the corps operations chief, its telecommunications chief, five bodyguards, four crew and the commander's chief of staff, he said. Ghori said all bodies had been recovered and transported to Herat city. Sayar, in his 50s, was a parachute specialist, he said.