The head of the Nigerian Army has visited soldiers in the northeastern town of Baga, telling troops that the conflict against Boko Haram will soon be over.

Lieutenant General Kenneth Minimah flew by helicopter to the fishing hub on the shores of Lake Chad and spent about 30 minutes on the ground, an AFP correspondent accompanying him said.

"The war is almost ended. We will liberate Dikwa, Bama, Gwoza, Marte and other places in a few days' time," Minimah told troops on the brief visit.

Boko Haram fighters overran Baga on January 3 and are thought to have killed hundreds, if not more, in what is feared to be the group's worst massacre in the six-year insurgency.

The military said on Saturday that the remote town in the far north of Borno state was retaken after two days of fighting, killing "a large number of terrorists".

Defence chiefs have published dozens of photographs purporting to show vehicles, arms and ammunition used by the Islamists that were destroyed in the fighting.

The offensive is part of a fight-back by Nigeria and regional powers against Boko Haram to secure and stabilise the restive region to make voting possible at the general election on March 28.

The vote was initially scheduled for February 14 but delayed by six weeks because military top brass claimed that troops would be unavailable to provide security on polling day.

President Goodluck Jonathan and his ruling Peoples Democratic Party (PDP) have been accused of playing for time to revive their election campaign in the face of a strong opposition challenge.

On Monday, Jonathan said that "the tide has now definitely turned against Boko Haram", despite two bombings earlier that day that killed at least 27 in the north.

Minimah said the six-week deadline was "achievable", adding: "We are still within the timeframe.

"But six weeks should not be taken that everything must be attained because this is war."

He added: "Never again will Nigerians suffer this kind of large-scale destruction in the name of insurgency."