North Sudan has halted an oil shipment from landlocked South Sudan in a dispute over customs fees.
North and south Sudan are required to withdraw their forces 10 km on either side of the border.
South Sudan`s army said it clashed with northern troops in the disputed Abyei border region on Wednesday.
The UN said northern army deployed 15 tanks alone in one area in Abyei town.
The northern Army has accused the south of aiding Darfuri rebels.
S Sudan claims that the northern govt is funding militias in the south,
a S Sudanese official said.
Sudan`s Prez said southerners could not have dual north-south nationality.
South Sudan is set to hold a referendum on Jan 9, as part of 2005 peace deal.
Day in Pics: 1st October
Showbiz World - October 1, 2014
George Clooney - Amal Alamuddin grand Venice wedding