On Friday, Afghanistan banned the use of a fertilizer chemical which is also used to make bombs. The government gave the farmers and other holders of the dangerous chemical a month to turn in their supplies.

Afghanistan’s President Hamid Karzai’s office issued a decree banning the use, production, storage, purchase or sale of ammonium nitrate. The decision was made after an investigation showed militants had used the chemical in a series of bombings, according to a statement.

Violators who fail to turn in supplies will face court action, the decree said.

These fertilizer chemicals were used in the composition of explosives that had been utilized in attacks including the 2002 nightclub bombings in Bali, which killed 202 people, and the 1995 attack on a federal building in Oklahoma City with a 2-ton bomb that killed 168.

NATO-led forces already have been confiscating the chemical compound, urging Afghan farmers to use fertilizer containing urea nitrate instead. Ammonium nitrate fertilizer has been used to make about 95 percent of the bombs in Afghanistan, according to security think tank Globalsecurity.org.

The government also ordered training for police and border customs house workers to detect the chemical.

Afghanistan’s government gave U.S. and allied forces permission to confiscate ammonium nitrate in September, and troops have been seizing huge quantities of fertilizer in return for compensation.

A joint force of NATO and Afghan troops found a truck carrying 10 tons of suspect fertilizer in the southern province of Kandahar earlier this month.

Protesters, meanwhile, blocked roads and chanted angry slogans against the United States and the Afghan government for a second day southwest of Kabul, amid mounting anger over the killing of four people in a village by NATO forces in volatile Ghazni province.

NATO said Wednesday’s raid in the Qara Bagh district targeted a Taliban commander and the four killed were suspected insurgents, including a 15-year-old boy shot while allegedly reaching for a soldier’s gun. But villagers insisted the dead were civilians.

Provincial police chief Khial Baz Shirzai also said the four killed in Wednesday’s raid were militants and the protests were organized by the Taliban to foment unrest.

The conflicting claims reflect growing impatience among Afghans over the presence of NATO-led forces, even though a recent U.N. report showed the number of civilian deaths attributed to allied troops had dropped sharply over the past year. The report blamed most civilian casualties on Taliban suicide bombings and other attacks.

International and Afghan security forces have stepped up operations as the U.S. and its allies begin sending 37,000 reinforcements to try to rout the Taliban. Militants also have increased their campaign with a series of attacks, including an assault on the Afghan capital on Monday.