Two separate suicide bombs struck Afghanistan on Wednesday, one of them against a US-led military base, leaving one person dead and several wounded, officials and a witness said.
The extremist Taliban movement said it was behind an attack in a district of Khost province on the eastern border with Pakistan but there was no immediate claim of responsibility for one in Helmand province in the south.
Two attackers wearing military uniforms had tried to enter the international military base in Khost's Gurbuz district, said provincial government spokesman Khaiber Pashtun.
"One of them walked out of the car and opened fire on police and the other exploded the car," Pashtun said. Police returned fire and killed the man on foot, he said.
Two people were hurt but it was not immediately clear who they were, he said.
The US and Nato military forces confirmed there had been an incident but said it was too early to say what had happened.
International military helicopters were overhead soon after the attack and a plume of dust and smoke rose into the air, an AFP reporter said.
A spokesman for the Taliban, Zabihullah Mujahed, said one of his group's "friends" had blown up a bomb-filled Russian Jeep outside the base.
In Helmand, a bomber who was on foot blew himself up near a police vehicle in the provincial capital of Lashkar Gah, provincial police chief Mohammad Hussain Andiwal told AFP.
"Two policemen were wounded and two civilians passing by were also wounded in the incident," he said.
A witness named Abdul Satar said a man had died after the explosion, possibly from natural causes as he appeared not to have been wounded in the blast.
Taliban insurgents are particularly active in Helmand, where Afghanistan's opium and heroin production is its highest and is said to finance the militants.
In another attack on police, four Taliban were meanwhile killed in a gunfight that erupted after they ambushed a convoy in the western province of Badghis province, a police spokesman said.
Three policemen were wounded in the attack, said the spokesman for western Afghanistan, Abdul Mutalib Raz.
The hardline Islamic militia, which was in government from 1996 to 2001, has stepped up attacks in recent weeks with around dozen policemen and a dozen civilians killed in violence Tuesday - one of the bloodiest days in weeks.
Afghan and international military forces have several operations under way against the militants.