South Sudan’s minister Luka Biong Deng of the national government has resigned, saying war crimes had been committed in the disputed Abyei region.
Luka Biong Deng said he could no longer work with the party of President Omar al-Bashir in the unity government.
He is a senior official in the south's ruling party, which led South Sudan’s independence in July.
The two sides have fought for decades before agreeing to hold a referendum for the southern independence.
Northern troops seized the territory of Abyei during the weekend after southern forces had ambushed a convoy of its forces in the area, killing 22 people.
It is assumed that about 20,000 people have fled the town, which is now deserted.
We had hoped that we could form two viable states in good relationship with each other, but those in Khartoum do not seem interested in peace, he said in the resignation statement.
He also added that the war crimes in Abyei are being committed by President Bashir's National Congress Party, and said he “could not in good faith continue to take part in such a government.
The Jan. 9 referendum vote split the oil-rich south from the north, while both sides stake a claim to Abyei, which lies on the border between the two regions.