Sudanese security on Sunday arrested the leader of the opposition Sudanese Congress Party Ibrahim al-Sheikh from En Nahud, a town of the North Kordofan State.

Sudanese security on Sunday arrested the leader of the opposition Sudanese Congress Party Ibrahim al-Sheikh from En Nahud, a town of the North Kordofan State, a party official said.

"Tens of police vehicles besieged al-Sheikh's residence in En Nahud before taking him into custody," Bakri Youssef, the party's spokesman, told media outlets.

He said authorities are accusing the opposition leader of acting against the constitutional regime, a crime that is punishable by death.

Youssef described the charge as "politically-motivated" because the party had turned down Sudanese President Omar al-Bashir's dialogue invitation in January.

Congress Party's General Secretary Abdel Kayoum Awad said the prosecution has charged Sheikh with undermining the constitutional order by spreading "harmful lies" after he blamed the government for the recent violence in Darfur in a speech on Saturday.

The charge of undermining the constitutional order, which Mahdi has also been accused of, can lead to the death penalty, a government official said previously.

Mahdi, a former prime minister, was arrested on May 17. He was also charged with "insulting the state security forces" by accusing them of participating in the Darfur unrest.

In response to the arrest, Mahdi's Umma party withdrew from the national dialogue talks.