United Nations peacekeepers should be more active in monitoring violence in Sudan's south ahead of an independence referendum next year, the oil-producing region's main party said on Saturday.

South Sudan won autonomy from the north of Africa's largest country in a 2005 peace deal ending 22 years of civil war, and will vote in the referendum due in January 2011 on whether to become a fully independent nation.

Analysts believe the south is likely to secede in the vote.

A senior Sudan People's Liberation Movement official, Mr. Yasir Arman, said it had evidence President Omar Hassan al-Bashir's ruling northern National Congress Party was trying to destabilise the south by arming proxy militias in the semi-autonomous region.

'The United Nations should verify and should be present in all the places where there are violations of the security arrangements,' Reuters quotes Arman as telling reporters.

'This is the mandate of the United Nations force here - they should take this mandateā€¦ seriously.'

The United Nations mission said it was committed to its mission. 'We are discharging our duties according to our mandate,' UN spokesman Ashraf Eissa said.

The peacekeeping mission was deployed to monitor a 2005 north-south peace deal ending Africa's longest running civil war which claimed two million lives.