Tuesday's accord called for an end to attacks on refugee camps
Sudan's military has denied accusations that it attacked a Darfur rebel group, a day after the two sides signed a goodwill agreement.
The Justice and Equality Movement (Jem), Sudan's most active rebel group, said the military launched air raids that left a number of casualties.
An army spokesman reportedly blamed another faction for Wednesday's attack.
Both sides sealed a goodwill agreement in the Gulf state of Qatar on Tuesday, but did not sign a ceasefire.
BBC world affairs correspondent Mark Doyle says fighting and peace talks often take place at the same time in Sudan.
'Going nowhere'
Speaking to the BBC's World Today programme, Jem spokesman Dr Jibril Ibrahim said: "The government has started a campaign of aerial bombardment in a wide area of east Jabal Marra, in addition to bombing an IDP camp, called Fallujah, where aerial bombardment killed a family and there are a lot of casualties.
"The source of water is destroyed and a lot of animals are also killed in the area.
"If we get the result like the one we are getting, I am afraid these talks are going nowhere," he added.
However, army spokesman Osman al-Aghbash told AFP news agency: "There was no fighting between the army and the Justice and Equality Movement.
"The fighting was between the Jem and the Minni Minnawi faction of the Sudan Liberation Army (SLA)," he said.
The SLA, a former rebel group, signed a peace deal with the government in 2006.
Despite the faction's leader, Mr Minnawi, becoming a presidential adviser, the faction has allegedly continued to attack other rebel groups.
Tuesday's Doha agreement aimed to pave the way for broader peace talks and included confidence-building measures calling for an end to attacks on refugee camps and a bilateral prisoner exchange.
But hanging over the accord is a proposed war crimes indictment of Sudan's President Omar al-Bashir.
Khartoum has rejected any suggestion the accord is a ruse to stave off any International Criminal Court arrest warrant.
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