Ending a three-year moratorium on the death penalty, Afghanistan executed 15 prisoners by gunfire, including a man convicted of killing three foreign journalists during the U.S.-led invasion, the prisons chief announced Monday.

The United Nations protested the executions, which could complicate the missions of some NATO nations here.

The mass execution took place Sunday evening according to Afghan law, which calls for condemned prisoners to be shot to death, said Abdul Salam Ismat, who oversees Afghanistan's prisons.

The crimes committed by those executed included murder, kidnapping and armed robbery, but officials said no Taliban or al-Qaida fighters were among the prisoners.

Until it was ousted in late 2001, Afghanistan's hard-line Taliban regime carried out executions in public, many of them at the Kabul stadium. The new government pledged to the international community it would halt executions, and had carried out only one previously, in 2004.

The 15 deaths could complicate relationships between the government and some NATO countries with military forces here. Foreign troops often hand over captured militants to the Afghan government, raising the question of whether countries that do not use the death penalty might stop surrendering prisoners.

The Netherlands was one of the first to criticize the Afghan announcement, calling the executions "extremely unwelcome." But it also said Dutch troops would continue to transfer militants to the Afghan government, saying it had an agreement protecting those prisoners from execution.

Anger over the executions also could prove a snag for NATO's efforts to get its member nations to send more troops to Afghanistan. NATO has some 40,000 soldiers here but commanders complain they need more helicopters, mobile troops and instructors to train the Afghan army.

"The fact that we have not fully been able to live up to the promises that nations have made is a point of concern for me," NATO Secretary-General Jaap de Hoop Scheffer said Monday in Denmark before the executions were announced.

Among those executed was Reza Khan, who was convicted of adultery and the murder of one Afghan and three foreign journalists in 2001. The four were pulled from their cars, robbed and shot near the eastern city of Jalalabad while driving toward Kabul six days after the Taliban abandoned the capital under heavy U.S. bombing.

The four were Australian TV cameraman Harry Burton, Afghan photographer Azizullah Haidari of the Reuters news agency, Maria Grazia Cutuli of Italian newspaper Corriere della Sera and Julio Fuentes of the Spanish daily El Mundo.

Also executed was Farhad, who is also known as Pahlavan and like many Afghan used only a single name. He was involved in the 2005 kidnapping of Italian aid worker Clementina Cantoni; she was freed after three weeks.

Tom Koenigs, head of the U.N. Assistance Mission in Afghanistan, said the U.N. had expressed its concern over the use of the death penalty many times in the past.

"The United Nations in Afghanistan has been a staunch supporter of the moratorium on executions observed in Afghanistan in recent years," Koenigs said. "I expect Afghanistan to continue working towards attaining the highest human rights standards and ensuring the due process of law and the rights of all citizens are respected."

The government's official announcement of the executions came on state television Monday evening, saying said Karzai ordered the executions following a decision by a special commission he set up to review rulings by the Supreme Court.

"After all the discussions and after looking back over the cases ... in order to prevent future crimes, such as murders, armed robberies, kidnappings, and to maintain the stability of the country, (Karzai) approved the prisoners' death sentences," a statement read over the news said.

Karzai's spokesman, Humayun Hamidzada, had told The Associated Press last week that Karzai was taking "extreme care in execution cases."

"He has been holding on to these cases because he wants to make sure that the justice is served and the due process is complete. He personally does not like executions, but Afghan law asks for it, and he will obey the laws," Hamidzada said.

The Dutch Foreign Ministry expressed distress at the executions.

"For the Netherlands, the abolition of the death penalty is one of our priorities in terms of international human rights policy," spokesman Bart Rijs said. "We had understood there was a moratorium on the death penalty in force."

Rijs said Dutch troops would continue to hand over prisoners because the Netherlands had signed a memorandum of understanding with Karzai's government guaranteeing those inmates would not be executed. Rijs said there were 10 such prisoners and all were believed in good health.

Amnesty International said six countries were responsible for 91 percent of all known executions worldwide last year: China, Iran, Iraq, Pakistan, Sudan and the United States. Eighteen other countries also carried out executions, the group said.