A prominent Afghan opposition commander from Faryab province, known as Engineer Mohammed Naseem Mehdi, has defected to the Taleban authorities.

Mr Mehdi told the BBC he had joined Taleban because the opposition was unable to establish a proper Islamic government in the country.

Correspondents say his defection is seen as another blow to the northern opposition after the defection last week in Bamiyan province the leader of a breakaway faction of the Hezb-i-Wahdat party, Mohammed Akbari.

Mr Mehdi had been associated with the Hezb-i-Islami party of Gulbuddin Hekmatyar, who is now in Iran.

He was also a deputy leader of the Junbesh-i-Mili party of General Dostam, who is currently in exile