Mauritanian Justice Minister Abidine Ould El Kheir was traveling to Mali Tuesday, on a visit that is being seen as an attempt to improve cooperation on fighting al- Qaeda in North Africa.
Officials requesting anonymity linked the visit with the ongoing trial in Mauritania of a suspect accused of taking part in the kidnapping of two Spanish aid workers.
The aid workers were captured late last year and are being held by an al-Qaeda affiliated group in northern Mali.
A French hostage, who had been kidnapped while carrying out development projects in poor regions of northern Africa, was executed by the Islamist militant group last month.
France, which has declared war against the group, has given support to Mauritania in its recent offensive against al-Qaeda in North Africa, which includes increased military operations.
Mali and Mauritania are seen by the West as needed allies in their attempt to defeat al-Qaeda.
Nouakchott had recalled its ambassador in Bamako last February to protest the release of a Mauritanian militant linked to al-Qaeda.