Tuareg rebels are demanding greater autonomy
The authorities in Mali say the army has destroyed the most active Tuareg rebel group's main base.
The defence ministry said a number of rebels and weapons had been seized in the operation in Tinsalak, close to the border with Niger.
But the rebel group - led by Ibrahim Ag Bahanga - said the government had found a base abandoned six months ago.
The group did not join several other Tuareg factions which recently returned to peace talks with Mali's government.
The defence ministry statement said the base was destroyed on Monday and journalists would be invited to view it next week.
The BBC's Martin Vogl in the Malian capital, Bamako, says it is difficult to check claims from either side given that the site lies in a remote and sparsely inhabited desert.
But such a find would be a timely boost for the Malian army, our correspondent says, given that it celebrated its 48th anniversary on Tuesday.
Mali's President Amadou Toumani Toure marked the milestone by pledging that "all operational means will be mobilised" against the rebels.
Our correspondent says a showdown may be on the way as the president has been increasingly adopting a tough line since the rebels raided a military base in northern Mali last month leaving at least 20 people dead.
Both sides signed a peace deal in 2006 in Algiers, but clashes have continued in the north.
Under the agreement, the rebels were to drop their demand for autonomy in the Kidal region while the government pledged to speed up development in three northern regions of Mali.
Three rebel groups united and recently announced a return to the peace process, denouncing Ibrahim Ag Bahanga's group for refusing to commit to the talks.
The Tuaregs, a historically nomadic people living in the Sahara and Sahel regions of North Africa, have had militant groups in Mali and Niger engaged in sporadic armed struggles for several decades.