Bamako, Mali (CNN) -- Islamist rebels in Mali have taken over a town in the middle of the country, a rebel leader and a resident said Saturday.
Douentza is in central Mali, about 110 miles (175 kilometers) from the key town of Sevare, which is in a buffer zone between the rebel-occupied north and the south.
Chaos has rocked Mali since a military ruler overthrew the democratically elected president in March, shaking one of West Africa's most stable democracies.
Two Islamist groups, MUJAO and the al Qaeda-linked Ansar Dine, now control Douentza, according to Ansar Dine military leader Omar Hamaha.
He said Ansar Dine had allowed the Ganda Izo militia to set up base in the town so they could join Ansar Dine, but the Ganda Izo people had "betrayed" them.
"We have become aware that there are intelligence offers and security agents of the Malian army among them," Hamaha said. "It's why we have decided to take over Douentza and disarm the so-called Ganda Izo militiamen."
A resident of Douentza, Adama Guindo, said the Islamists disarmed the militia without shooting. He described groups of Islamist fighters riding in vehicles mounted with heavy weapons inside the town.
The coup leader who overthrew the democratically elected president stepped down in May and transferred power to a civilian transitional government, but ethnic Tuareg rebels and other Islamist militants have taken advantage of the uncertainty to seize control of the northern part of the country, including Timbuktu.
Members of the Malian army are currently based in Sevare for training and possible military intervention in the north.