Parliament in Sudan has approved a bill re-instating a multi-party system after a nine-year ban by the military government.

The bill was passed after some members of parliament walked out, saying they didn't have enough time to express their views.

The bill which comes into force next year, permits at least one-hundred eligible voters to form what is described as a political association.

However, a registrar appointed by the head of state has the right to dissolve any association considered to have violated the constitution.