KHARTOUM, Sudan - An Islamist opposition leader detained after suggesting Sudan's president give himself up to face war crimes charges was released Monday after seven weeks, his son said.

Hassan Turabi was sent home from an eastern Sudanese prison at dawn. The 76-year-old's deteriorating health was a factor in the release, said his son, Siddique Turabi. He was held without charge, he said.

Turabi is a leading Islamic fundamentalist ideologue. He was once an ally of President Omar al-Bashir and was the driving force behind a 1989 military coup that brought al-Bashir to power. The two fell out in 1999, and Turabi set up his own party. He has been jailed several other times.

There was no immediate comment from the government Monday, and Turabi was not immediately available for an interview. Another leader of Turabi's Popular National Congress Party was also released.

The opposition leader was arrested Jan. 14 after telling reporters that al-Bashir should give himself up to the International Criminal Court to save Sudan from internal strife. Last week, The Hague, Netherlands-based court issued an arrest warrant for the president on charges of war crimes and crimes against humanity in Darfur.

He is accused of directing attacks against civilians in Darfur, where up to 300,000 people have died and 2.7 million have been driven from their homes, according to the UN.

The conflict began six years ago with an uprising by ethnic African rebels accusing the Arab-dominated government of neglect and discrimination. Sudan's government responded with a counterinsurgency and is accused of unleashing militia fighters who have carried out atrocities.

Authorities briefly detained Turabi last year after al-Bashir's party accused him of backing a Darfur rebel attack on the capital last year.

Other than Turabi, no one in Sudan has openly suggested that al-Bashir hand himself over to the ICC even though some former rivals have said the president should "deal" with the court's accusations.

The government rejects the ICC and the charges against al-Bashir.

Amnesty International had protested Turabi's detention, calling it arbitrary and saying it was carried out in response to his comments about the president.