In a raid on a military base in Nampala in central Mali on July 19, 17 Malian soldiers were killed and 35 injured.
The attack was claimed both by the Islamist Ansar Dine and a newly formed group.
Ansar Dine is a mainly Tuareg group that controlled areas of Mali's northern desert together with Al-Qaeda in the Islamic Maghreb (AQIM) and a third local group in early 2012.
Although the Islamists were largely ousted by an ongoing French-led military operation launched in January 2013, sporadic assaults from desert hideouts are common.
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An Ansar Dine video had been posted online hours earlier, showing five men in army fatigues, and identified as soldiers taken hostage on July 19 during the Nampala raid.
Distributed by private Mauritanian news agency Al-Akhbar, the video shows the five men seated in front of a black jihadist flag held up by two masked men.
Speaking on condition of anonymity, a defence ministry source confirmed the men seen in the video were indeed five of the missing Malian soldiers.
Sidibe said some 500 additional troops and 100 military vehicles have been dispatched to the camp since the attack, which has been assaulted several times since 2015.
Malian President Ibrahim Boubacar Keita yesterday chaired a meeting of the country's defence committee.
After the gathering, Defence Mnister Tieman Hubert Coulibaly confirmed six troops were missing, and said he had seen the footage distributed online.
He did not comment on the video, however.