A criminal court in Egypt on Wednesday sentenced an Egyptian man to life imprisonment over charges of colluding with Al-Qaeda and undertaking armed "hostile acts" against African states.

Investigations revealed that Mahmoud Hassan, 28, has embraced jihadism since 2009 and had ties with members of the militant Islamist group overseas via the internet with the aim of toppling regimes in Arab countries and applying Islamic law, or sharia, the public office said in a statement on Thursday.

The probe showed the accused undertook "hostile acts" in Somalia and Kenya together with Al-Qaeda commanders there.

Hassan was the group's communication operative who gave training to other members on operating wireless devices, GPS technology and explosive circuit technicalities, the statement said.

It added that the defendant has admitted his affiliation with Al-Qaeda.

He was arrested in Kenya and detained there for three months over charges of staying illegally, and was later caught by Egyptian authorities upon his return.

Egypt has been hit by a deadly Islamist insurrection orchestrated by Al-Qaeda-inspired militants since the army's ouster of Islamist president Mohamed Morsi last summer.

An Al-Qaeda offshoot, the Islamic state, has seized extensive swathes of Syria and Iraq, where it has declared an Islamic caliphate. The group was the target of a US-led air strike in Syria this week.

The group has urged insurgents in Egypt's Sinai Peninsula to carry on with their attacks against police and troops as well as beheadings.