Fresh doubts have been raised over claims by Afghan officials that they have captured one of the Taleban's top commanders, Mullah Dadullah.
Mullah Dadullah on al-Jazeera TV last February
The officials told the BBC on Friday that he had been seized in the southern province of Kandahar.
But a man claiming to be Mullah Dadullah later told the BBC he was still free, and not far from Kandahar.
Separately, a number of soldiers have been killed in renewed fighting with insurgents in the south of the country.
Insurgents ambushed a convoy of Afghan government forces in Helmand province, resulting in an unconfirmed number of casualties on both sides, including at least four Afghan soldiers.
In separate fighting in the Kandahar region, two French special forces soldiers were killed and another injured.
One American soldier died and six others were injured in a gun battle in Uruzgan province.
Meanwhile, a man identifying himself as Mullah Dadullah has contacted a number of news agencies by satellite phone to say he was free.
During his two calls to a BBC Pashto service correspondent in Pakistan, he said he was the one-legged Islamic commander who had been leading Taleban insurgents in Kandahar and Helmand provinces.
The man said he would continue to attack Afghan and foreign troops in the area.
The man said it was possible the authorities had mistakenly arrested one of the several thousand innocent people who had lost their limbs by stepping on a landmine during the ongoing Afghan conflict.
Mullah Dadullah was a member of the Taleban's 10-man leadership council before the US-led invasion in 2001.
The news of Mullah Dadullah's arrest earlier had sent a wave of excitement in Kabul, the BBC's Zaffar Abbas says.
It was being treated as a huge success of the coalition forces since they launched the latest offensive against the anti-government insurgents in the south, our correspondent says.
But now, he says, the Afghan authorities may have to come up with some solid evidence to convince the world that Mullah Dadullah was in their custody.
There has been no official confirmation of the arrest from the Afghan government or US military.