Five African aid workers who were abducted in Niger in mid-October have been freed alive, while a sixth has died after being shot by the al-Qaida-linked kidnappers, the workers and their employers said Saturday.

Five Niger nationals "were freed today and are currently in Niger," while their colleague Aime Soulembaye from Chad has "died from his wounds," Niger's Befen and Chad's Alerte-Sante aid agencies said in a statement.

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.

An Islamist rebel group in northern Mali said Thursday it had freed three of seven Algerian diplomats kidnapped during the takeover of the city of Gao in April.

"We eventually agreed to free three of the seven hostages with us," said Adnan Abu Walid Sahraoui, spokesman for the Movement of Oneness and Jihad in West Africa (MUJAO), without specifying when they were released.

In a shady corner of a remote, sun-baked village square in Niger, aid worker Boubacar Halirou wraps his measuring tape around the skinny arms of a hungry toddler and identifies another victim of severe malnutrition.

Halirou, who works for the local aid group Befen, is crisscrossing the region looking for emaciated youngsters as the impoverished west African desert nation faces a drought-driven food crisis.

The U.N. refugee agency launched an urgent cash appeal on Friday to help thousands uprooted by clashes in Mali, saying that the emergency there had been overlooked.

"This is now an emergency that is six months old and yet we have received only 13 percent of the funds" that are needed, said spokesman Andre Mahecic.

There is a risk of "terrorist" groups setting up in the deserts of northern Mali, French President Francois Hollande warned Monday after talks with Niger's President Mahamadou Issoufou in Paris.

"There is a threat of terrorist groups setting up in northern Mali. There is outside intervention that is destabilizing Mali and setting up groups whose vocation goes well beyond Mali, in Africa and perhaps beyond," Hollande said.

Niger officials on Saturday held talks in Tripoli on security issues including Saadi Gadhafi and other members of the former regime who are sheltered in Niger and wanted by Libyan authorities.

Libyan Prime Minister Abdel Rahim al-Kib said that his country takes "no chances" when it comes to the threat posed by remnants of the former regime sheltered in Niger.

Booms from rocket launchers and automatic gunfire crackled around Mali's fabled town of Timbuktu, known as an ancient seat of Islamic learning, for its 700-year-old mud mosque and, more recently, as host of the musical Festival in the Desert that attracted Bono in January.

On Sunday, nomadic Tuaregs who descended from the people who first created Timbuktu in the 11th century and seized it from invaders in 1434, attacked the city in their fight to create a homeland for the Sahara's blue-turbanned nomads. Their assault deepens a political crisis sparked March 21 when mutinous soldiers seized power in the capital. The Tuaregs have rebelled before, but never have they succeeded in taking Timbuktu or the major northern centers of Kidal and Gao, which fell Friday and Saturday as demoralized government troops retreated.

Niger will not extradite Saadi Gadhafi even though the son of the slain Libyan leader violated his asylum conditions with "subversive" comments in a television interview, officials said Saturday.

"Our position remains the same -- we will hand Saadi Gadhafi to a government that has an independent and impartial justice system," government spokesman Marou Amadou told reporters in Niamey.

Saadi Gadhafi, one of the sons of Libya's slain dictator Moammar Gadhafi, has said a nationwide rebellion is brewing against the country's new rulers as he vowed to return to his homeland.

"I will return to Libya at any time," Saadi Kadhafi told al-Arabiya television by telephone from neighboring Niger, where he took refuge after the fall of Tripoli which ended his father's 42-year iron-fisted rule of Libya.