WASHINGTON (AFP) – US rights groups hailed the International Criminal Court's decision to accuse Sudanese President Omar al-Beshir of genocide and urged world powers to work toward his swift arrest and trial.

They also expressed concern the ICC's ruling, which added genocide to the list of charges against Beshir, could prompt further retaliation from the Khartoum government against civilians.

"Today's ruling brings us one step closer to getting justice for the many thousands of victims of Beshir's campaign of calculated violence and destruction of livelihoods," Physicians for Human Rights CEO Frank Donaghue said in a statement.

In 2006, his group documented atrocities committed against civilians in Darfur, where the United Nations says up to 300,000 people have died since 2003, when ethnic minority rebels took up arms against the Arab-dominated regime for a greater share of resources and power.

Khartoum says 10,000 people have died.

US President Barack Obama should make clear his support for peace in Sudan "by sending the message that consequences will result from any retaliation against Sudanese civilians as a result of this warrant, and by building stronger international support for this warrant," said John Prendergast, who co-founded the Enough Project.

Donaghue agreed it was now "more imperative than ever" that the trial process against Beshir go forward.

"At the same time, the international community must ensure that these charges do not result in the targeting of civilians, aid workers or peacekeepers. The place for President Beshir to dispute these charges is in The Hague," he added.

During his visit to the region next week, US special envoy on Sudan, Scott Gration, will renew his call for Beshir to "cooperate fully" with the court in The Hague, State Department spokesman Philip Crowley said earlier.

But activists urged more action from the Obama administration.

"The United States government should reaffirm its support for the ICC's pursuit of justice in Darfur," Genocide Intervention Network president Mark Hanis said, urging Washington to work with the UN Security Council and ICC member states to ensure the "swift" enforcement of all related arrest warrants.

Save Darfur Coalition's acting president, Mark Lotwis, pressed world powers to "vigilantly monitor for any threats or acts of violence or other repression against civilians, Sudanese human rights activists, aid workers or peacekeepers."

In March last year, the ICC issued a warrant for Beshir's arrest on charges of war crimes and crimes against humanity, its first ever for a sitting head of state, but stopped short of accusing him of genocide.