Exiled former Palestinian security chief Mohammed Dahlan says his conviction for defamation by a West Bank court is aimed at keeping him from running in promised presidential and parliamentary elections.

Dahlan, who lives in exile in the United Arab Emirates, was convicted in absentia by a Ramallah court in March and sentenced to two years in prison, but the ruling was only made public this week.

Writing in Arabic on his Facebook page late on Wednesday, Dahlan said the timing "obviously aims to disrupt... my resolved participation in the next presidential and parliamentary elections."

The revelation comes as Palestinian president Mahmud Abbas's Palestine Liberation Organisation (PLO) and the Islamist Hamas, who recently inked a unity deal, were poised to unveil a new government of technocrats which will pave the way for long-delayed elections.

Dahlan, a bitter rival of Abbas, accused the president of using the court "as a tool to serve his personal grudges and purposes against me."

If the sentence is upheld on appeal, it would bar Dahlan from standing as a candidate.