(CNN) -- The leader of Sudan's best-armed rebel group says an offensive against Khartoum could come soon if the Sudanese government rejects renegotiating the Darfur peace agreement.
London-based Gibril Ibrahim, foreign secretary of the Justice and Equality Movement, or JEM, said in e-mails with CNN that the movement would prefer to achieve peace by putting pressure on President Omar al-Bashir's regime to sit down at the negotiating table again.
But Ibrahim said that although JEM has been engaging in negotiations with Khartoum since before the armed struggle in Darfur began in 2003, the government has failed to convince rebels that it is a genuine peace partner.
"Unless we take the war to the seat of the throne of the regime in Khartoum, the regime will never care to rectify the situation or faithfully seek peaceful settlements," Ibrahim said.
He added that the JEM's leader, Khalil Ibrahim, who had recently returned to Darfur from his year-long exile in Libya, is reorganizing the civil and military organs of the movement and working to create a coalition bringing various armed movements and the political opposition together.
That would include the two factions of Darfur's other main rebel group, the Sudan Liberation Movement or SLM, Gibril Ibrahim said.
Sudanese State Minister Amin Hassan Omar discredited the threats in a phone interview with CNN.
"We don't believe that they have this capacity or the force" to topple the government, Omar said. "That would be like committing suicide. ... They would be considered terrorists."
While the JEM and other movements confirmed they will join in a peace workshop slated for October 27-28 in Washington, the government has declined to participate.
The peace agreement -- signed in July by only one Darfuri rebel group, the Liberation and Justice Movement, or LJM -- was "the document of the people of Darfur, not just some sort of negotiation between the government and the LJM," Omar said in explaining the government's rejection of new talks.
He added that resistance movements have been invited to join the Doha agreement in the three months since it was signed but instead choose to threaten with force.
"We are not intimidated by their talk," Omar said. "Our alliance is with the people of Darfur."
This year alone, some 70,000 people from Darfur, a province in western Sudan the size of Spain, have become displaced by aerial bombardments, according to a June 2011 Human Rights Watch report.
Omar refused to comment on accounts of at least 100 aerial bombardments this year, saying the allegations were made by Darfuri rebels and that United Nations-African Union and other international observers have a presence in the area.
Ibrahim said the military tactics Khartoum had used during the civil war in southern Sudan -- which became an independent country on July 9 --and those used in Darfur were very similar to those the government applied in the current conflicts in Sudan's two flashpoint border states, South Kordofan and Blue Nile.
"It is no secret that JEM forces in South Kordofan are fighting the forces of the regime by the side of the SPLA-N," the JEM leader said, referring to the Sudan People's Liberation Movement/Army-North. That group is the northern faction of South Sudan's main political party, which has been engaged in war against Khartoum in South Kordofan since June.
Since summer, more than 250,000 people have been forced to flee their homes in South Kordofan and Blue Nile, the United Nations says.
An estimated 300,000 people have died in the Darfur conflict and well over 2 million have been displaced since 2003. Al-Bashir and two other officials are wanted for crimes against humanity and genocide in Darfur by the International Criminal Court.