A prominent Sudanese human rights activist detained for several months has been charged with spying for foreign embassies, an offence punishable by death, a prosecutor said on Monday.

Mudawi Ibrahim Adam, an engineering professor at the University of Khartoum, was arrested in December by security forces as part of a crackdown on opposition leaders and activists.

Prosecutor Babikir Abdel Latiff said that charges have been filed against Ibrahim Adam and that the activist will soon face trial.

"He and some others are involved in running a criminal organisation and carrying out spying and intelligence activities for foreign embassies in return for money," Abdel Latiff said in a statement.

"They are also charged with publishing lies about (government forces) using chemical weapons, and distorting the image of the state."

In September, rights group Amnesty International said Sudanese forces had carried out dozens of suspected chemical weapons attacks in a mountainous area of war-torn Darfur that killed up to 250 people, including many children.

Sudanese officials including President Omar al-Bashir have steadfastly rejected the report.

Under Sudanese criminal law, the charges against Ibrahim Adam are punishable by death.

Several opposition leaders and activists were detained in December in an attempt to crush widespread protests against a government decision to raise fuel prices.

Ibrahim Adam, who has worked extensively on human rights causes in Sudan, has been arrested several times before for his work. The government shut down a development organisation he headed in 2009.