Aid agencies in Sudan say rebels in the south are mobilising their fighters and press-ganging new recruits in preparation for another round of fighting.

The agencies say the forced conscripts are being taken to bases in Uganda where they are kept under armed guard.

One experienced aid worker told the BBC it was clear preparations were being made for renewed conflict.

A spokesman for the rebel Sudan People's Liberation Movement said it was rounding up former soldiers because it was expecting government attacks. The BBC East Africa correspondent says the rebels have come under pressure since failing to prevent the Islamic government in Khartoum exploiting oil fields in the mainly Christian south.