Locals have reported seeing busloads of soldiers moving northwards towards Mocimboa da Praia on the highway from Pemba, the capital of Cabo Delgado province.
Neighbourhood leaders have also been advising villagers to vacate their homes and head to Palma to minimise civilian losses in the event of clashes.
Troops are preparing an operation to recover a strategic port in northern Mozambique that was seized by jihadists three weeks ago, sources say.
Islamist militants occupied Mocimboa da Praia, the focus of a scheme to develop the region's offshore gas wealth, on August 12 following days of attacks.
