Complex sentence: Raissi's case remains a contentious issue in Algeria, whose government refuses to sign an agreement with Britain about extraditing hijackers until Britain acknowledges that their treatment of Raissi was flawed.
Split into simpler sentences: Raissi's case remains a contentious issue in Algeria. And Algeria is delaying signing an agreement with Britain over extraditing hijackers until Britain acknowledges that their treatment of Raissi was flawed.