Sudan's foreign ministry summoned the EU representative in Khartoum on Friday to protest a statement issued by Brussels that criticized nationwide elections due to start next week.

EU foreign affairs chief Federica Mogherini said in a statement Thursday that the polls "cannot produce a credible result" because of President Omar al-Bashir's failure to establish a genuine national dialogue, which he announced last year.

Two top Sudanese political figures were freed from detention Thursday without explanation, days before national elections, their lawyer said.

Farouk Abu Issa and Amin Makki Madani were detained in December after signing an agreement to unite opposition to President Omar al-Bashir, who is standing for reelection on Monday.

The EU said Thursday that next week's Sudan elections, widely expected to see President Omar al-Bashir extend his 25-year rule, cannot produce a "credible" result.

Bashir faces 15 little-known challengers while the main opposition parties are boycotting the vote in an impoverished country riven by deep political, religious and tribal divisions.

Sudanese President Omar al-Bashir on Wednesday lashed out at international peacekeepers in Darfur during an election speech in El Fasher, one of the war-torn region's main towns.

Bashir told supporters at an election rally that the United Nations and African Union peacekeeping mission in Darfur (UNAMID) wasn't needed to solve the unrest plaguing the region, where insurgents have battled his government since 2003.

Rebels in Sudan's South Kordofan said Sunday they had captured a lorry carrying ballot boxes to polling stations for nationwide elections due next week, vowing to disrupt voting in the conflict-hit region.

The Sudan People's Liberation Army-North "ambushed and captured a vehicle loaded fully with ballot boxes" on Saturday on the road linking the state capital Kadugli with the town of Dilling, spokesman Arnu Lodi said.

Sudan is providing ground troops as well as warplanes for a Saudi-led military intervention against Shiite rebels in Yemen, the defense minister said on Thursday.

Saudi warplanes launched strikes on the Huthi rebels on Thursday in a bid to stop their advance on embattled President Abedrabbo Mansur Hadi's refuge in the main southern city of Aden.

South Sudan's parliament voted Tuesday to extend President Salva Kiir's mandate by three years, an official said, formally ditching any plans for elections this year in the civil war-torn country.

The move has been seen as going against peace efforts by regional mediators, who have been pushing President Kiir and rebel leader Riek Machar to share power in a transitional government.

Egypt, Ethiopia and Sudan Monday agreed a preliminary deal on a controversial dam project that Cairo feared would reduce its share of vital waters from the Nile.

The leaders of Egypt, Ethiopia and Sudan all gathered in Khartoum to sign the agreement of principles on Ethiopia's Grand Renaissance Dam project.

Sudanese rebels said on Sunday they had launched a "lightning" assault on a government garrison in the conflict-hit Blue Nile region, with the army saying the attack was repulsed.

Sudan People's Liberation Army-North forces "carried out a lightning attack on al-Gabanit garrison" on Saturday some 45 kilometers (28 miles) southwest of Blue Nile state capital Ed Damazin, spokesman Arnu Lodi said.

A South Sudanese rebel group has freed 250 child soldiers -- including a girl as young as nine, the U.N. children's agency said on Sunday, but warned that thousands were still being forced to fight.

The rebel Cobra Faction is also set to release another 400 child soldiers in the next two days under a deal with the government, out of total of 3,000 it holds, UNICEF said.