Sudan's ruling party has warned of serious violence in the flashpoint Abyei region, a day after the  government of the country's breakaway south accused Khartoum of plotting its ouster. 
      

Al-Dirdiri Mohammed Ahmed, the National Congress Party's chief  negotiator on Abyei, warned of "a lot of skirmishes" unless the southern army  withdraws thousands of "irregular" troops from the volatile district by  Monday. 
      

But the prospects of the southern Sudan People's Liberation Army  (SPLA) bowing to the NCP's demands have dimmed. 
      

On Saturday, the southern government walked out of pre-independence  negotiations, accusing Khartoum of arming southern militia groups and planning  its ouster ahead of southern Sudan's planned secession in July. 
      

Dirdiri told journalists in Khartoum that a deadline for the  withdrawal of around 2,500 SPLA troops in police fatigues, agreed to by both  sides under an accord reached in January, expired on Monday. 
      

"If the SPLA is not going to withdraw the police ... the situation  in Abyei might deteriorate, and could prove to be very serious within the  coming few days," he said. 
      

A peace accord reached on January 17 called on all forces to  withdraw from the disputed border district except for special joint units of  northern and southern troops alongside UN peacekeepers. 
      

Tensions there have been high since the January referendum on  independence for the south, in which southerners voted almost unanimously to  secede from the north. 
      

A simultaneous plebiscite on Abyei's own future, as to whether it  joins the north or south, was postponed indefinitely, with the NCP and south's  ruling Sudan People's Liberation Movement (SPLM) at loggerheads over who  should be eligible to vote. 
      

At least 70 people were killed and three villages razed in clashes  earlier this month between fighters from the Arab Misseriya tribe, which  supports the Khartoum government, and the Ngok Dinka people, who back the  south. 
      

On Friday, a US monitoring group said it had satellite images that  showed armed groups backed by the armies of both north and south Sudan  reinforcing their positions in the area. 
      

Dirdiri blamed the latest in Abyei on the SPLA-backed forces, whom  he accused of killing indiscriminately and slaughtering Misseriya cows for  food. 
      

In turn the south has repeatedly accused the Misseriya nomads, who  herd their cattle south in the dry season in search of water and grazing  pastures, of fomenting the violence with Khartoum's support. 
      

Pagan Amum, the southern official who announced the decision to  abandon talks with the north, said on Sunday that the NCP was arming Arab  tribes all along the border in a policy of attempted genocide. 
      

"They want to carry out genocide like they have done to the African  tribes in Darfur," he told a news conference in Juba. 
      

Heavy clashes on Saturday between south Sudanese troops and a rebel  militia accused of links to Khartoum in the southern border town of Malakal,  in oil-rich Upper Nile state, left 42 people dead, SPLA spokesman Philip Aguer  said Sunday, updating an earlier death toll of 30. 
      

Aguer said two of the dead were SPLA soldiers and the rest rebels. 
      

South Sudan has witnessed a wave of deadly clashes with militia  groups in Jonglei and Upper Nile state in recent weeks that have left hundreds  dead and revived the war of words with Khartoum. 
      

Ties between the two sides had appeared to have improved during  January's largely peaceful referendum. 
      

The future of Abyei is the most sensitive of a raft of issues that  the NCP and the SPLM have been trying to resolve ahead of southern  independence in July, which include borders, citizenship, security and debt. 
      

Presidential adviser Salah Gosh, who heads the NCP team in the  joint political committee, said on Sunday that the SPLM decision to quit the  talks was a negotiating tactic. 
      

"I think they will come back. They have no other way to resolve the  situation," he said. 
      

"They think that if they explode this balloon it will create a new  environment for trying to gain in Abyei, and on other post-referendum issues  like petrol share," he added.