A group of Sudanese military officers were sentenced to between two and five years in prison on Sunday for their role in a coup attempt last year, the army and a defense lawyer said.

"The accused persons were convicted of attempting to undermine the constitutional and security system and threaten the country's unity and harm the armed forces by the use of force," army spokesman Sawarmi Khaled Saad said.

Demonstrations have taken place across Sudan's troubled Darfur region against an international donors' conference which begins on Sunday in the Gulf state of Qatar, a civil society activist said on Saturday.

Some of the 1.4 million people displaced by Darfur's decade-long conflict protested on Friday at their camps near North Darfur's state capital El Fasher, and in Kalma camp, South Darfur, said the activist, who asked not to be identified.

Egypt's President Mohamed Morsi said during his first visit to Sudan on Friday that cooperation between the Islamist regimes in Cairo and Khartoum does not pose any threat and yet they both face "enemies".

"We in Egypt and Sudan are integrated, and you will find enemies for this integration," Morsi stressed before thousands of people, including his Sudanese counterpart President Omar al-Bashir, at al-Noor mosque in Khartoum North.

The "revolutionary" regime of Egyptian President Mohammed Morsi should foster tighter ties between its people and those of neighboring Sudan, veteran Islamist Hassan al-Turabi said on Friday.

Speaking after he and other political party figures met the visiting Islamist leader, Turabi said grassroots links must be developed because Morsi's regime "is a popular government elected by the people."

Direct road links between Egypt and Sudan will open soon, Egyptian President Mohamed Morsi said on Thursday, beginning a two-day visit which Khartoum has called "historic".

Morsi's first trip to the neighboring country, which Egypt jointly ruled with Britain until 1956, comes nearly a year after his election.

Sudanese authorities released six political prisoners early on Tuesday, an Agence France Presse photographer reported, after President Omar al-Bashir vowed to free all political detainees.

The six men walked free to tearful relatives waiting outside Kober Prison in Khartoum North.

Sudanese President Omar al-Bashir said on Monday that he will release all political detainees, a move welcomed by the opposition as tensions ease with South Sudan.

"Today, we announce a decision to free all the political prisoners and renew our commitment to all political powers about dialogue," Bashir said in a half-hour speech opening a new session of parliament.

People power may have come to modern-day Egypt and not Sudan, but the unearthing of ancient pyramids in Egypt's southern neighbor shows that greater social equality existed there 2,000 years ago, a French archaeologist says.

Three years of digging by a French team at Sedeinga, about 200 kilometers (120 miles) from the Egyptian border, has unearthed 35 pyramids that emphasize the contrast between the two ancient cultures, said Claude Rilly, director of the mission.

Sudan's vice-president has misled the public by inviting rebels for talks, the insurgents in South Kordofan state said on Thursday, calling for dialogue under a U.N. Security Council resolution.

President Omar al-Bashir's regime had long rejected negotiations with the Sudan People's Liberation Movement-North (SPLM-N), who have been fighting for almost two years in the South Kordofan and Blue Nile regions.

Three Sudanese opposition members were detained after police forcibly dispersed a rally demanding the release of other opponents of the regime held for several weeks, their leader said on Sunday.

"We dispersed but after I left the place... three young men were arrested," Farouk Abu Issa, head of the opposition alliance, told Agence France Presse.