JUBA, Sudan (Reuters) — Campaigners said on Monday they had found serious discrepancies in reports of Sudan’s oil revenues which could mean Khartoum’s government was underpaying its strife-torn south by hundreds of millions of dollars.

The findings by UK-based Global Witness could spark a political storm in Sudan, where relations between its Muslim north and mostly Christian south have remained tense since the end of their two-decade civil war in 2005.

Under the 2005 peace accord, both sides agreed to share the country’s oil wealth, with the south receiving half the state revenues from the oil drilled from its territory.

Global Witness said it had found revenues from some oilfields published by Sudan’s Ministry of Finance “among the figures used to calculate the southern share” were lower than revenues for the same oilfields published by operator China National Petroleum Corporation (CNPC).

No one from Sudan’s Ministry of Finance or of Energy and Mining was immediately available for comment.

The study “raises serious questions about whether the revenues are being shared fairly,’’ said a statement by Global Witness, a group which campaigns against conflict and corruption related to natural resources.