A suicide bomber has blown himself up in front of one of the largest US military bases in Afghanistan, killing two Afghan children, a senior police official says.
The Taliban claimed responsibility for the attack, saying it was a retaliation attack against Koran burning by the US soldiers.
The incident took place in front of Bagram air base, north of Kabul, one of the biggest US-controlled military base in Parwan province of Afghanistan on Monday evening.
Zia ul Rahman, deputy provincial police chief, said two Afghan children between 14 and 15 years old were killed and four others were wounded when a suicide bomber blew himself up.
No coalition troops were injured in the blast, he said.
Separately, another suicide bomber detonated his explosive-packed vest in the eastern city of Jalalabad, the provincial capital of Nangarhar province, killing an intelligence agent and injuring 11 others, the Interior Ministry said in a statement.
The attacks came after a war of words between NATO and Kabul over whether the original burning of a Koran by US troops at Bagram was intentional or not.
The burnings of the Koran, and other religious texts, last month prompted violence that saw some 30 protesters killed, and six US soldiers murdered in revenge attacks. It also saw US President Barack Obama send a personal written apology to Afghan President Hamid Karzai.
Earlier on Monday, an Afghan investigator charged with probing the incident said he believed the burning of the Koran was deliberate.
"We believe it is intentional," said Maulavi Khaliqdad, a member of the panel established by Karzai.
"If they burnt one or two copies, then we could have said it could have been a mistake. But they took hundreds of such books to burn. Everyone knew those were religious books."
However, NATO secretary-general Anders Fogh Rasmussen, speaking in Brussels on Monday, said the burning of copies of the Koran was "unintentional".
"The preliminary results of the (NATO) investigations that have been initiated reveal that this incident was unintentional. The facts show that there was no malicious intent to mishandle religious material," he told reporters.
He described the incident as "very unfortunate", adding: "Our commanders in Afghanistan will make decisions about the appropriate next steps ... to avoid such incidents in the future."
Khaliqdad said his team's finding that the burning was intentional has been presented to Karzai and parliament.
"It is impossible if you collect that many books from a library ... Someone is responsible for this," he said. "We cannot accept that they say it was a mistake.
"A mistake is when someone does something without any knowledge or when someone is unaware," said Khaliqdad, who is also a member of religious Ulema Council of Islamic scholars and mullahs.
Khaliqdad said a senior Afghan army officer had asked the US military staff where the books were being taken before they were burnt.
"And they told him that the books were being taken to storage," he said. "But instead they were burnt."