Switzerland has urged an end to the latest violence in Sudan which erupted one week after a breakthrough in peace talks to end the country's civil war.
The Swiss foreign ministry said in a statement on Wednesday that it was alarmed by the escalation of violence and the large number of civilian casualties.
The rebel Sudan People's Liberation Movement (SPLA) on Tuesday accused government troops of killing 1,000 civilians in a new offensive in the south of the country.
Bern appealed to the two parties to return to the negotiating table "to constructively continue the peace dialogue".
Switzerland helped to mediate a ceasefire agreement between the Sudanese government and the SPLA in January. Bern "noted with satisfaction" the latest pact signed on July 20.
The agreement stated that the country's Muslim leadership would only apply Islamic, or Sharia law in the Muslim north, and not in the predominantly Christian south.
"The cessation of violence by both parties is an indispensable prerequisite for the preservation and continuation of the only recently-achieved progress towards a political solution to the war that has raged continuously for almost 20 years," said the Swiss foreign ministry.
It repeated its willingness to promote national conciliation.
Sudan government denies re-igniting violence
The Sudanese government sternly denied SPLA allegations that it launched an offensive in the Western Upper Nile region on Friday. The Sudanese chargé d'affaires in Nairobi blamed the clashes on militias acting independently of Khartoum and said the rebel reports and death toll were exaggerated.
"What has been said by (the SPLA) is completely baseless," said Ahmed Dirdeiry.
The civil war began in 1983 when rebels took up arms against the Muslim-dominated northern government after the adoption of Sharia law in the largest country in Africa.
More than two million people have died during the fighting.
swissinfo with agencies
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