"The Popular Congress Party (PCP) is not at all involved in Darfur developments," Turabi told reporters at his party headquarters in Khartoum.
"Members of the (PCP) party who have registered with armed men in Darfur have done so without the consent of the party," Turabi said.
"All parties, including the ruling party, have members who have joined the armed groups there," he added.
"It is the government that is responsible for aggravating the situation in Darfur, by resorting to military action instead of talks, by encouraging tribal militias and inciting tribes against each other," Turabi said.
Sudanese authorities have arrested 27 PCP members of the party since last week, according to party official Bashir Adam Rahma.
The Darfur rebellion launched by the Sudan Liberation Movement (SLM) earlier this year has cost some 3,000 lives and displaced hundreds of thousands of people.
The war pits government troops and their Arab militia allies against rebels drawn mainly from the region's non-Arab minorities, who notably want the authorities to promote economic development in their isolated, arid region.
According to diplomatic sources, one of the Darfur rebel groups, the Movement for Justice and Equality, has been expanding with support from Turabi.
The Sudanese government recently accused both Eritrea and the PCP of backing the rebels, leading to a collapse in peace talks.