His administration has hailed Nigeria's exit from recession, successes against Boko Haram militants including the return of the kidnapped Chibok schoolgirls, road and railways construction, and loans for farmers, as highlights of the first term.

"The principal interest of this administration is to consolidate on the achievements of the last four years," the 76-year-old former military leader said in his first major public speech since his re-inauguration last month.

But critics have often found fault with Buhari's first term, when he was absent for long periods for health reasons, and economic improvement was largely down to improved oil prices.

Still, he won re-election in February with 56% of the vote, though turnout was just 36%.

"In the last four years, we have made solid progress," Buhari told an audience of government, military and traditional figures and foreign dignitaries during a celebration of the return to democracy in 1999.

"We can lift 100 million Nigerians out of poverty in 10 years," he promised.

Buhari said Nigeria's economy would grow 2.7% this year - but that was below the central bank's 3% forecast in March.

Economists have lamented Nigeria's sluggish growth since it climbed out of recession in 2017, with the population getting poorer as birth rates outpace economic expansion.

Buhari also signaled policy stability when he re-appointed as central bank governor Godwin Emefiele, a controversial figure for his first-term foreign exchange machinations to shore up the naira currency.

Meanwhile, violence has spread and is thriving across wide swathes of Nigeria's northwest, northeast and central states, often in places that were less troubled before Buhari's rule.

The only corruption being tackled, anti-graft activists and opposition politicians say, is that of Buhari's political enemies, while allegations against his allies are rarely followed through to prosecution.

Buhari said he would continue to build roads, fix the electricity grid and improve other infrastructure.

He also reiterated his support for agriculture.

"When economic inequality rises, insecurity rises. But when we actively reduce inequality through investments in social and hard infrastructure, insecurity reduces," he said.

"We are not daunted by the enormity of the task ahead.”

VOA