London - Muhammadu Buhari on Thursday vowed to "lead from the front" in the fight against Boko Haram if elected in the country's forthcoming election.
The former military ruler, who rejected descriptions of him as a "dictator", also argued against further delays to the election and said a free, fair and peaceful vote would boost democracy in Africa.
The leader of the All Progressives Congress (APC) has been seen as neck-and-neck with President Goodluck Jonathan in the closely fought election campaign.
Some have predicted that the People's Democratic Party (PDP) could lose power for the first time since Nigeria returned to civilian rule in 1999.
In a speech at the Chatham House international affairs institute in London, Buhari asserted that Nigeria had been failed by a consistent lack of leadership from Jonathan in the insurgency.
"Our soldiers have neither received the necessary support nor the required incentive to tackle this problem. Let me assure you that if I'm elected president, I vow to change that," he added.
"We will give them adequate modern arms and ammunition, we will improve intelligence gathering... we will be tough on terrorists and tough on its root causes... in the affected areas."
"No inch of Nigerian territory will ever be in the hands of the enemy," Buhari pledged, promising to return Nigeria to its former role as a stabilising force in west Africa.
The Islamist insurgency, which began in 2009, has left more than 13,000 people dead and forced more than one million others to flee their homes.
Also read: Buhari speaks at Chatham House in London
Jonathan and his administration have been widely criticised for failing to stop the violence, which has seen Boko Haram seize territory in the northeast and attack neighbouring countries.
Elections scheduled for February 14 were delayed as the military said ongoing operations with soldiers from Chad, Cameroon and Niger meant that troops could not provide security on polling day.
But Jonathan, his national security advisor and the head of the army have said that major gains will be made by the new election date, March 28, to allow voting to take place.
Critics have accused Jonathan and the PDP of delaying the vote to give them more time to seize back the momentum from the APC and Buhari said "any form of extension... will not be tolerated".
Instead, he said free, fair and peaceful elections could "trigger a wave of democratic consolidation in Africa" and help to strengthen democracy in the country.
The retired General, seen as an anti-corruption figure despite allegations of serious rights abuses by his regime in the 1980s, also responded to descriptions of himself as a former dictator.
"Let me say without sounding defensive that dictatorship was military rule, though some are less dictatorial than others," he said.
"I take responsibility for whatever happened under my watch. I cannot change the past but I can change the present and the future.
"So, before you is a former military ruler and a converted democrat who is ready to operate under democratic rules."