Bamako -- Al-Qaeda's North African branch on Wednesday released in Mali two Canadian diplomats, a German and a Swiss tourist kidnapped several months ago, but held on to two other Europeans, officials announced.

The kidnappers released Robert Fowler, UN special envoy to Niger and his assistant Louis Gay, who were snatched in December last year in Niger and two female tourists out of a group of four snatched in January.

A spokesman for the Malian presidency confirmed earlier reports from both a security source and a politician in the northern town of Gao.

"We confirm that the two Canadian diplomats, the German and the Swiss women were released today (Wednesday)," said spokesman Seydou Sissouma told AFP.

Later Wednesday, they arrive in Gao, said a spokesman for the governor there.

But the women's travelling companions -- the husband of the Swiss woman and a Briton -- are still being held.

The tourists, a Swiss couple, a German woman in her 70s and a British man who have not been named, were captured in January in the border zone between Mali and Niger as they were returning from a Tuareg cultural festival.

Malian officials, particularly local politicians, played a key role in securing the release of the hostages, said officials in Gao.

They said the Canadian diplomats were released first and it was only thanks to the Malian negotiators' insistence that the kidnappers finally agreed to set the women tourists free too.

Al-Qaeda's North African branch claimed responsibility for both kidnappings.

While the hostages were abducted in neighbouring Niger they were released in northern Mali close to the border.

The kidnapping marked the first time Al-Qaeda had targeted Niger, a mainly Muslim country that has been plagued by Tuareg uprisings in the north for the past two years.

The Malian authorities, especially local politicians, played a key role in securing the release of the hostages, sources said.

Initially the kidnappers had demanded the release of two of its Mauritanian members held in Mali. Officials there have said that one of them had since been killed in a traffic accident while being transferred between prisons.

The group reportedly also tried to exchange its captives for Islamists arrested in Europe, but it was not known if any of their demands had been met.

Wednesday's release came a month after the driver of the Canadian hostages who was kidnapped with them was released in Mali.

Shortly afterwards, the Malian authorities announced they had arrested the main suspect in the tourists' disappearance.

In October last year an Austrian couple, who had been snatched by the Al-Qaeda group while on holiday in Tunisia, were freed in north Mali following an eight-month kidnap ordeal.

The Sahel region, with vast stretches of inhospitable desert, is notoriously difficult to control. Rebel movements and other armed groups roam largely unhindered across it and over borders between the countries.

In the north of Mali and Niger, the authorities have faced uprisings by Tuareg rebels fighting for autonomy in their traditional desert homeland.

Al-Qaeda of the Islamic Maghreb has said it intended to unify armed Islamist groups in Tunisia, Algeria and Morocco as well as emerging groups in countries bordering the Sahara.

It has also claimed a series of deadly suicide bombings in Algeria, other attacks in the region and several kidnappings.

AFP/Expatica