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KHARTOUM, May 12 (Reuters) - Sudan arrested Islamist opposition leader Hassan al-Turabi and at least four top members of his party on Monday after the attack on Khartoum by Darfur rebels historically linked to him, aides said.

"Security forces came early this morning and arrested Turabi," Awad Babiker, Turabi's private secretary, told Reuters.

Khalil Ibrahim and other leaders of the Darfur rebel group, the Justice and Equality Movement (JEM), which attacked a suburb of Khartoum on Saturday, were supporters of Turabi in the past. But Turabi denies any support for JEM.

The attack was the first time fighting had reached the capital in decades of conflict between the traditionally Arab-dominated central government of Africa's biggest country and rebels from peripheral regions.

Turabi's son said the security forces arrested his father at his home about one hour after he returned from a conference of his Popular Congress Party in nearby Sennar state.

"They want to blame the party for what has happened," said Siddig al-Turabi.

Turabi was President Omar Hassan al-Bashir's ideologue until they split in a bitter power struggle in 1999-2000.

Since then Turabi has been in and out of jail but was released along with all other political prisoners after a north-south peace deal in 2005.

(Reporting by Opheera McDoom)

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