Despite cries of alarm from European politicians over the deaths of migrants in the Mediterranean, African leaders have been silent over an issue they fear underlines their weak governance, say campaigners.

For years Libya has been a stepping stone for Africans seeking to get to Europe, fleeing conflict, economic hardship and instability often in rickety, unseaworthy vessels.

Senegal said on Tuesday it had set up a crisis unit to help the families of migrants shipwrecked in the Mediterranean to get information about their loved ones.

The center will provide a hotline to enable families to get in touch with authorities who are "working hard to give people reliable and credible information", the government said.

The captain of a migrant boat that capsized in the Mediterranean's deadliest disaster in decades was arrested Tuesday on suspicion of causing the deaths of an estimated 800 people.

Prosecutors in the Sicilian city of Catania said they believed Tunisian national Mohammed Ali Malek, 27, was responsible for steering mistakes and the reckless overcrowding which led to the horrifying shipwreck off Libya on Sunday.

Senegal's former president Abdoulaye Wade called for a mass rally on Friday over the sentencing of his son for graft as his lawyers said they had filed an appeal.

Karim Wade, who was being groomed to succeed his father in the top job, got a six-year jail term on Monday after judges ruled he was guilty of "illegal enrichment" and fined him the equivalent of more than 210 million euros ($230 million).

Pro-democracy activists from Senegal and Burkina Faso arrested in Democratic Republic of Congo on suspicion of planning to destabilize the country will be expelled and banned from returning, the government announced on Wednesday.

"They will be expelled from the country. They are also being declared persona non grata," DR Congo government spokesman Lambert Mende told AFP. "It's the best solution we could find."

Senegal's President Macky Sall on Tuesday proposed a referendum on reducing his mandate by two years, a stance in contrast to several fellow African leaders criticized for clinging to power.

The pledge came with countries including Benin, Rwanda, Burundi and Congo-Brazzaville all said to be considering constitutional change to allow their leaders a third term in office.

More than 300 migrants were feared drowned Wednesday after their overcrowded dinghies sank in the Mediterranean, the latest boat disaster on the perilous crossing from Africa to Europe.

The victims were among migrants mainly from sub-Saharan Africa who had left the coast of Libya at the weekend in four small boats, the U.N. refugee agency said.

Peace and security will be the focus of a conference bringing together top American military brass and the heads of 35 African armies which opened in Senegal on Monday.

The meeting comes amid heightened concerns over conflict across the continent, with intensified Boko Haram bloodshed delaying elections in Nigeria, the Central African Republic struggling to recover from a coup and ethnic violence raging in South Sudan.

Algeria secured their spot in the quarter-finals of the Africa Cup of Nations on Tuesday thanks to a 2-0 win against Senegal in their last Group C game in Malabo.

On a dramatic evening, Riyad Mahrez set Algeria on their way with the opening goal inside 11 minutes, and for a long time it looked as if both sides would be heading through to the last eight.

Senegal reopened its land border with Guinea on Monday, pointing to the "significant efforts" of its neighbor in fighting an Ebola outbreak that has claimed thousands of lives.

People and goods can now "move freely by land between the two countries," the interior ministry said in a statement cited by the state-run Senegalese Press Agency.