LUSAKA, Oct 8, 2008 (AFP) - A Zambian court has been asked to decide whether electoral authorities can use a two-year-old voter roll in this month's presidential election, a lawyer said Wednesday.

Zambia is due to hold elections on October 30 to replace the late president Levy Mwanawasa, who died in August after suffering a stroke.

The Electoral Commission of Zambia (ECZ) said it will use the voter register from the last poll in 2006 as it did not have time to prepare a new one due to a constitutional requirement to hold the vote within 90 days of the president's death.

Kelvin Bwalya, a lawyer representing the pro-opposition Anti-Vote Rigging group, said he has filed a case in the Lusaka High Court challenging the decision to use the old register.

'We want the court to mandate the ECZ to register new voters ahead of the elections because most people will be defranchised,' said Bwalya.

Under Zambian law, voter registration is supposed to be carried out continuously, but a lack of resources has hampered that effort.

High Court Judge Philip Musonda is due to make a ruling this week.

Four candidates are contesting the elections, but the main contenders are acting president Rupiah Banda and populist opposition leader Michael Sata of the Patriotic Front.