KABUL, Afghanistan (AP) -- A roadside bomb killed a NATO soldier and wounded four others in southern Afghanistan on Sunday, while a Taliban ambush left eight Afghan security personnel dead, officials said.
The NATO soldiers were patrolling in the country's volatile south when an explosion ripped through their vehicle, NATO said in a statement.
"They were immediately evacuated for medical care ... (but) sadly one died of wounds inflicted by the explosion," it said.
NATO did not identify the nationalities of the dead and wounded soldiers, or the exact location of the blast. Militants regularly attack foreign and Afghan troops with roadside bombs in that part of the country.
In central Wardak province, meanwhile, Taliban militants fired rocket-propelled grenades from their vehicles at a convoy led by private security guards on Saturday, killing six guards and two police officers, said Wardak police chief Gen. Zafaruddin, who goes by one name.
The security contractors were guarding equipment on the main highway linking the capital with the country's south, when militants opened fire near Maydon Shahr, about 20 miles southwest of Kabul, Zafaruddin said.
This year has been Afghanistan's most violent since the 2001 U.S.-led invasion drove the Taliban from power. More than 6,300 people, mostly militants, have been killed in insurgency-related violence, according to an Associated Press count.
Meanwhile, the U.N.'s top representative here, Tom Koenigs, said he was "particularly concerned" that an Afghan consultant who worked for the U.N. remains jailed after he accompanied officials from the U.N. and European Union, allegedly to a meeting with Taliban commanders in Helmand province.
The government asked the two officials to leave the country last week, and detained the Afghan consultant.
"We've made it clear to the Afghan government that we want to see him released as soon as possible, because even the government has publicly stated that no U.N. staff member was involved in any secret talks," said Aleem Siddique, a spokesman for the U.N. mission.
Koenigs said "underlying assumptions" from some elements within the Afghan government were misunderstandings. That was an apparent reference to allegations that the two officials met with and may have handed money over to Taliban leaders.
He said the U.N. was not involved in any intelligence operations or paying money to any insurgents.
Koenigs, the head of the U.N. Assistance Mission to Afghanistan for the last two years, left his post on Sunday. Bo Asplund, a Swedish national, is now the officer in charge until a permanent head is named.
Paddy Ashdown, a former leader of Britain's opposition Liberal Democrats who served previously as Bosnia-Herzegovina's international administrator, is a leading candidate to replace Koenigs.
After two years as special representative, Koenigs said he leaves the country with both hope and concern.
"Afghanistan is moving from being a country decimated by decades of conflict to a progressive Islamic democracy, striving to improve the lives of its people," he said. "However, I share the same concern as the Afghan people for the security situation, particularly in the south of the country."
Koenigs said the U.N. assistance mission will continue to back the rights of victims of Afghanistan's nearly three decades of conflict, saying reparations are needed for past abuses. He said acknowledging past abuses is not a barrier to reconciliation, but rather is a "prerequisite for future peace and stability in Afghanistan."
Also Sunday, Taliban commander Mansoor Dadullah -- who a spokesman for the militants said had been kicked out of the militia -- said he believed Taliban leader Mullah Omar has not signed off on the dismissal order, and blamed the report on a "conspiracy" by his enemies.
"It's not true that Mullah Omar kicked me out of the Taliban," Dadullah told The Associated Press by telephone. "If Mullah Omar wanted me to leave the Taliban, then he would send me the message and I would put down my weapons because he is our top commander."
Dadullah rose in the militia's ranks as an important commander in southern Afghanistan after his brother, Mullah Dadullah, was killed during a military operation in Helmand province in May. Mullah Dadullah was the highest-ranking Taliban commander killed since the U.S.-led invasion of Afghanistan in 2001.