A suspected suicide bomber killed 15 Afghans and wounded 14 more in eastern Afghanistan, close to the border with Pakistan on Tuesday, a NATO spokesman said.
Also on Tuesday, Afghanistan's intelligence chief said President Hamid Karzai was warned of a weekend assassination plot against him, while admitting failings by security services.
Amrullah Saleh told Parliament the plot to kill Karzai was hatched last month and the gunmen had rented the hotel room they opened fire from 45 days before the attack.
Stepped up attacks
The Taliban have vowed to step up suicide attacks this year to undermine the faith of Afghans in the ability of their government to provide security and sap support in the West for the continued presence of international troops in the country.
Initial reports said 25 Afghans were wounded in Tuesday's blast near the district center of Khogiani, a town south of the city of Jalalabad, but the number of wounded was later revised to 14, said Major Martin O'Donnell, a spokesman for the NATO-led International Security Assistance Force.
It was not clear if the victims were civilians or members of the Afghan security forces.
International forces were in the area at the time of the blast, but escaped injury and were now helping to treat the wounded and evacuate them to hospital, O'Donnell said. The international force was investigating the explosion, but suspected it was caused by a suicide bomber.
Residents said Afghan forces and civilians were among the dead. One resident, reached by telephone from Kabul, said the dead included 11 Afghan security force members and two children.
Taliban insurgents launched more than 140 suicide attacks across the country targeting foreign and Afghan government forces last year, but most of the victims — around 200 — were civilians.
Fighting has steadily increased in the south and east of the country in recent weeks as Spring arrives and mountain snows begin to melt.
Attempt on Karzai
Karzai and other dignitaries managed to escape unharmed from Sunday's assault during a ceremony in Kabul marking Afghanistan's victory over the Soviet occupation of the country in the 1980s. Three other people, including a lawmaker, died.
Three of the attackers were also killed in a gunbattle with security forces after the assault, Karzai's government said, but the Taliban said three other insurgents got away.
"We had technical information ... that this work would happen," intelligence chief Saleh told a National Assembly session broadcast live on national television. "We passed this information to the national security (adviser) and to the president of Afghanistan."
Despite stringent measures by security services to protect the event, "the result is that we failed," Saleh said.
An Afghan intelligence official has said about 100 people were rounded up for questioning after the attack. Some of those questioned have since been freed, officials say. The official spoke to The Associated Press on condition of anonymity because he was not authorized to speak to the media.
Saleh, Defense Minister Abdur Rahim Wardak and Interior Minister Zarar Ahmad Moqbel were summoned to explain to lawmakers what happened Sunday.
Daud Sultanzoy, a lawmaker, demanded all three security officials resign — although there was no immediate sign that would happen.
Government's fragile grip
The attack in the Afghan capital underscored the fragile grip of Karzai's government in the face of Taliban insurgents and raised questions about its demand for Afghan police and army to take greater control of security. U.S. and NATO-led troops provide security in much of the country now.
But the White House said it was unfair to criticize Afghan security forces because insurgents launched an attack.
"When it comes to dealing with terrorists like the Taliban or al-Qaida, they just have to have even ... a little bit of an impact for everyone to say that they had a big victory," White House press secretary Dana Perino said Monday.
The attack has added to unease in Kabul, which has been spared the worst of the violence as fighting escalated between the Taliban and international troops.
Reuters and The Associated Press contributed to this report.
