Unknown people have attacked the offices of two of Iraq's top four Shiite clerics in the central city of Najaf with sound bombs, a security official there said on Wednesday.

"The office of Grand Ayatollah Bashir al-Najafi in central Najaf city was attacked with a sound bomb on Tuesday evening," the official said, adding that "there was an attack with a sound bomb that targeted the office of Grand Ayatollah Ishaq al-Fayadh on Sunday evening."

At least 21 civilians and three soldiers were killed on Wednesday in violence across Syria, activists said, 13 days after a tenuous truce came into effect.

Regime forces killed six people in the northwestern province of Idlib, four in the Damascus suburbs of Harasta and Douma, four in the southern province of Daraa, three in the northern province of Aleppo, two in the central province of Hama, a person in the eastern province of Deir Ezzor and another in the central province of Homs, the Local Coordination Committees, the main activist group spurring protests on the ground, reported.

Algeria's Prime Minister, fearing a wide scattering of votes in the May 10 general elections in which 44 parties are running, Wednesday urged voters to support the main ruling coalition partners.

Ahmed Ouyahia, who heads the National Rally for Democracy (RND), belonging to a three party political alliance loyal to President Abdelaziz Bouteflika, called for "useful" votes.

The first batch of 10,000 former Libyan rebels arrived on Wednesday in Jordan for training in order integrate into their country's interior ministry, the kingdom's security department said.

Under a deal signed between Amman and Tripoli in December, the former rebels who helped topple Moammar Gadhafi's regime last year will receive training at an international police center east of Amman, deputy police chief Major-General Mohammed Raqqad said in a statement.

A handful of U.N. observers resumed their tour of Syrian hot spots on Wednesday as envoy Kofi Annan urged the fast deployment of the full, 300-strong mission and voiced alarm about persistent violence.

Nine civilians were reportedly killed across country, taking to nearly 300 the number of people who have died since a tenuous ceasefire went into effect on April 12.

Turkish authorities found no weapons after searching a German-owned vessel docked at a southern port last week on suspicion of smuggling arms to Syria, an official report has disclosed.

"As a result of the investigation, nothing was encountered which can be described as weapons, munitions or military materials inside any of the checked goods," according to the report which was signed by Turkish customs officials.

A 5.0-magnitude earthquake struck western Algeria's Chlef region on Wednesday, but did not cause any injuries or infrastructure damage, the Centre of Astronomy, Astrophysics and Geophysics Research said.

Tremors were felt up to 200 kilometers away in the capital Algiers, as well as in the neighboring region of Ain Defla.

A bomb attack carried out by "terrorists" wounded four Bahraini policemen in a Shiite-populated village overnight, the official BNA news agency said on Wednesday.

"A terrorist explosion targeted security forces that were escorting firefighters... on their way to the scene" of a blaze in the village of Diraz, BNA reported, citing a senior police official.

South Africa on Tuesday accused U.N. Security Council powers of "conveniently" ignoring human rights abuses in the disputed territory of Western Sahara.

The council again rejected growing demands for the U.N. peacekeeping force in the Moroccan-controlled territory to have a permanent rights investigation duty.

Syria is still seeing "unacceptable" levels of violence, international envoy Kofi Annan told the U.N. Security Council on Tuesday, after dozens of people were killed across the country despite a ceasefire.

"The situation in Syria continues to be unacceptable," Annan told a closed-door meeting. He spoke after a car bomb rocked central Damascus, wounding three people, while nearly 60 people were killed across the country a day earlier ahead of the deployment of 300 U.N. peace observers.