Prominent Sudanese politician Hassan al-Turabi, a veteran Islamist and leader of the opposition Popular Congress Party (PCP), has died at the age of 84, medical sources said Saturday.

Turabi, one of the country’s most influential political figures, formed the PCP in 1999 to challenge long-serving President Omar al-Bashir and his ruling National Congress Party, with which Turabi had previously been aligned.

He was rushed to a hospital Saturday after suffering a heart attack, the sources said.

Turabi, who hosted al Qaeda leader Osama bin Laden in the 1990s, was elected speaker of Parliament in 1996 and was close to Bashir before a bitter power struggle and split in 1999.

He was jailed several times after forming the PCP, one of a handful of opposition groups that accuse Bashir of clinging to power despite a promise to step down in 2015.

Bashir has ruled since a 1989 military coup and has weathered rebellions, economic crises and an indictment by the International Criminal Court on suspicion of having orchestrated war crimes in Sudan’s Darfur region.