Fresh fighting erupted Saturday in northern Mali between ethnic Tuaregs and an unidentified armed group, security sources told Agence France Presse, the latest violence in the wake of a French-led campaign that drove radical Islamist fighters from major cities.

Tuaregs of the Azawad National Liberation Movement (MNLA) were fighting what one source said "seemed to be Arab fighters" near the northern town of Tessalit, where suicide car bombers killed three people on Friday.

Britain called on Chad on Saturday to arrest Sudanese President Omar al-Bashir while he visits N'Djamena for a regional summit and to hand him over to the International Criminal Court.

Chad is one of the countries signed up to the ICC's founding treaty which are legally bound to arrest Bashir, who is wanted for war crimes, crimes against humanity and genocide in the long-running Darfur conflict.

About 1,800 Chadian soldiers have entered the northern Mali city of Kidal to "secure" what was the last stronghold of Islamist rebels, the French defence ministry said on Tuesday.

A ministry official said French forces, now numbering 4,000 in Mali, also took control and were securing the city's airport following paratrooper reinforcements.

Chad's government on Tuesday said a team of international experts have not been able to find any links between the hospitalization of 38 children and their recent vaccinations against meningitis.

The children fell ill in the northern village of Gouro and were admitted to hospital after being vaccinated in a government campaign against the disease between December 11 and 15.

Thirty-eight children from northern Chad have been hospitalized after being vaccinated for meningitis in a government campaign, the health minister said Monday.

"During the last phase of the vaccination campaign organized at Gouro (near the Libyan border) on December 11 to 15, 2012, unusual reactions were noted," Health Minister Mamouth Nahor N’Gawara told AFP.

Chadian President Idriss Deby on Monday appointed chief of staff Djimrangar Dadnadji as the country's new prime minister following the resignation of Emmanuel Nadingar, state radio announced.

"I have the honor to hand in... my resignation as prime minister, head of government, three years after you appointed me in this post. Today I have come to the end of my mission," Nadingar wrote in a resignation letter read out on the radio.

West African leaders Saturday called for greater international involvement in Mali as they met to speed up the deployment of regional troops to boost a French-backed offensive to halt an Islamist onslaught.

The emergency summit in Ivory Coast's main city Abidjan was also attended by French Foreign Minister Laurent Fabius who clearly said it was time for the Africans to take over and "as soon as possible", adding that this was "the aim of our meeting."

A group of French aid workers went on trial Monday on charges they tried to illegally bring 103 children from Chad to France for adoption, claiming they were orphans from Darfur.

Six aid workers with the Zoe's Ark non-governmental organization went on trial in Paris, though two of the leading suspects were to be tried in absentia after refusing to show up for the proceedings.

U.N. chief Ban Ki-moon Wednesday urged world leaders "not to abandon" the Sahel region, but urged caution amid calls for military intervention to flush out armed Islamist rebels in northern Mali.

"The region needs your attention, your focus. Do not abandon it and regret it later," Ban told a high-level meeting on the sidelines of the U.N. General Assembly.

Nigeria's military said Wednesday that two suspected Boko Haram Islamists who were trying to smuggle heavy weapons into the country were killed by troops during a shootout on the border with Chad.

The alleged insurgents were caught carrying rocket-propelled grenades, Kalashnikov rifles as well as other assorted ammunition and weaponry, Sagir Musa, a military spokesman in the northeastern town of Maiduguri told Agence France Presse.