Nigeria's military on Wednesday told Boko Haram militants that talks remained an option, as top brass visited troops in the group's traditional stronghold.

"To the insurgents, the dialogue table is still open, else the national power is available to the armed forces to crush the insurgency," army chief of staff Lieutenant General Kenneth Minimah said in the northeastern city of Maiduguri.

Minimah was accompanied on the visit to the city -- scene of a daring Boko Haram strike on a military barracks last Friday -- by his air force counterpart Air Marshal Adesola Amosu.

Nigeria's counter-insurgency effort has largely involved ground troops, supported by air power, but a wave of deadly attacks recently has prompted questions about whether the strategy is effective.

Some defence analysts have previously urged the government to open channels of communication with more moderate elements within Boko Haram and broaden the counter-insurgency fight to include economic and social development in the impoverished north.

On Tuesday, National Security Adviser Sambo Dasuki unveiled a new, broader counter-terrorism policy of "soft power" programmes to complement military force.

Minimah, appointed in January after President Goodluck Jonathan sacked his entire military top brass, said the visit was aimed at boosting morale while Amosu said he was satisfied with "the impact we have already inflicted on the enemy".

The air force's role was "to harass the enemy and to convince them that they need to come either to the table or drop their guns", he added.