Niger's military says more than 500 government soldiers with armored tanks and heavy weapons are heading by road to the southeast town of Diffa to free hostages being held there.
Reports say it may take them up to 24 hours to arrive by road since they could not be airlifted because of reports the rebels control the Diffa airport.
Residents say soldiers who mutinied on Wednesday were holding several local government officials captive Thursday.
The soldiers are demanding the resignation of the nation's army chief, better pay and direct negotiations with Niger's prime minister.
The rebel soldiers took control of the town on Wednesday, seizing a radio station to broadcast their demands. They told the townspeople their dispute was with the government, not the citizens of Diffa.
Niger's defense minister, Sabiou Dady Gaoh, has vowed the government will punish the rebellious soldiers. At an emergency cabinet meeting Wednesday, he said the military will take all measures necessary to bring the mutineers to justice.
Diffa remains under a nighttime curfew imposed by the mutinous soldiers.
Niger has a long history of military coups. Observers say this week's unrest has been the most serious since the country returned to civilian rule two years ago.