Nearly half a tonne of explosives, remote-controlled devices and other materials were recovered on Monday from the Dawatul-Haq school in Khost province, in the southeast of the country,provincial intelligence chief Mohammed Sadiq Tarakhil said on Tuesday.
The former Islamic school (madrassa), 10km west of Hassanzay village in the Mandozay district, had not been used for the past year and was left vacant, he said.
"This is the first time terrorists have used a madrassa as a terror facility in Afghanistan," he said.
"Yesterday we discovered some 400kg of explosives, remote-controlled devices, two remote-controlled bombs, fuses, rockets, 200m of wire and vehicle registration plates from the madrassa," he said.
Remote-controlled bombs are a favourite tool of the ousted Taliban government, which has used them for a string of roadside attacks on US and Afghan forces during renewed unrest since the start of the year.
The Taliban often use remote-
controlled bombs in their attacks
Two suspected fighters were arrested later in the area but Tarakhil refused to comment if the arrests were related to the bomb facility.
Separately, in neighbouring Paktia province, 17 landmines were discovered and defused on the main road from the provincial capital, Gardez, to Sayed Karam district, which is routinely used by Afghan and US-led forces.
Ali Ahmed Mobariz, the province's intelligence chief, blamed the attack on an alliance of the al-Qaida network, the Taliban and the Hezb-e-Islami group run by former Afghan premier Gulbuddin Hekmatyar.
Afghan officials frequently make such claims.
Four US soldiers were wounded in a roadside bomb explosion on the same road earlier this month.
Three policemen and a suspected Islamic fighter were killed in an ambush on a police vehicle in eastern Afghanistan, an official said on Tuesday.
The local police chief was also injured in the attack in the Dawlat Shah district of Laghman province on Monday night, provincial governor Shah Mohammad Safi said.
Four US soldiers were wounded in
a roadside bomb explosion
It was not immediately clear who carried out the attack, but similar incidents have been blamed on remnants of the ousted Taliban government, which ruled Afghanistan from 1996 to late 2001.
"The search for the attackers is ongoing in the area," the governor said.
Intelligence officials said earlier this month they had captured three Pakistani nationals who wanted to assassinate former US envoy Zalmay Khalilzad in the same province, east of the capital Kabul.