(AFP) - Security is set to top the agenda at an African Union summit Monday, after host Mauritania warned of regional security failings in the face of jihadist violence, as French soldiers were targeted in a fresh attack in Mali.

A bombing aimed at French soldiers on patrol in the country's troubled north killed four civilians and injured over 20 people, including four soldiers, Malian and French officials said.

On Friday, a suicide bombing hit the Mali headquarters of the five-nation force known as G5 Sahel, adding to concerns about how it can tackle the jihadist groups roaming the region.

It was the first attack on the headquarters of the five-nation force, which was set up with French backing in 2017 to fight jihadist insurgents and criminal groups in the vast and unstable Sahel region.

In total, four separate attacks killed 15 people in Mali in three days, as the West African nation prepares to go to the polls on July 29.

The leaders of the G5 Sahel states -- Mali, Burkina Faso, Mauritania, Niger and Chad -- met Sunday on the sidelines of the AU summit, a diplomatic source said, to prepare for talks with French President Emmanuel Macron.

Security concerns are high on the agenda at the AU summit attended by more than 40 African heads of state and government as well as Macron, who will meet G5 leaders to focus on progress made by the force.

Mahamadou Issoufou, Niger's president, condemned the security situation after his country's defence ministry reported that a Boko Haram attack in southeast Niger left 10 soldiers dead.

"These attacks should strengthen our determination to fight terrorism to ensure our populations' security," he said.

Mauritanian President Mohamed Ould Abdel Aziz said the Friday bombing "hit the heart" of the region's security and lashed out at a lack of international help.

The Al-Qaeda-linked Support Group for Islam and Muslims, the main jihadist alliance in the Sahel, claimed the attack in a telephone call to the Mauritanian news agency Al-Akhbar.

- 'UN doors closed' -

"It was a message sent by the terrorists at this precise moment when we are getting organised to stabilise and secure our region," Aziz told France 24 television.

"If the headquarters was attacked, it is because there are so many failings we need to fix if we want to bring stability to the Sahel."

The G5 aims to have a total of 5,000 troops from the five nations but has faced funding problems.

It operates alongside France's 4,000 troops in the troubled "tri-border" area where Mali, Niger and Burkina Faso meet, and alongside the UN's 12,000-strong MINUSMA peacekeeping operation in Mali.

Underscoring the regional insecurity, four Malian soldiers were also killed on Saturday when their vehicle drove over a landmine in the central Mopti region.

Aziz said the G5 was a "sovereign initiative" of Sahel states that face not only security problems but drought, poverty, unemployment and trafficking.

"We are not at all satisfied with the help we are getting. We also feel that the doors of the United Nations are closed."

- Free trade, migration -

African leaders will also look at a planned ceasefire in South Sudan's civil war and at the detente between Ethiopia and Eritrea, whose relations have been poisoned for decades.

Rwandan President Paul Kagame, who holds the presidency of the 55-nation AU, will make a call to promote free trade.

Currently, African countries only conduct about 16 percent of their business with each other, the smallest amount of intra-regional trade compared to Latin America, Asia, North America and Europe.

Meanwhile, discussing the flow of migrants from Africa to Europe, Aziz told France 24 it was a "result of the 'destruction' of Libya by Western strikes".

"I am not saying that all responsibility lies with Europe, we must deal with the problem upstream," said the former general who took power in a coup in 2008 and has since been elected twice.

© Agence France-Presse