President Muhammadu Buhari has kept a low profile since his grand return from sick leave on Saturday.

Buhari disembarked his plane in Abuja on Saturday to a military salute and was cheered by hundreds of people who lined the streets as his motorcade drove to the presidential villa.

But the president, known locally as the Lion of Africa, is again working from home and missing weekly cabinet meetings, as he did during his previous, two-month, stay in Nigeria between absences for treatment for an undisclosed ailment in Britain.

The refusal to disclose details of Buhari's illness has caused speculation about whether the 74-year-old is well enough to run Africa's most populous country and biggest economy.

In a televised address on Monday, Buhari looked thin but sounded stronger than at his last broadcast in June. He walked unaided off the plane when he arrived on Saturday, though at a slow pace, holding rails on either side of him.

He had reduced his working day to a few hours after returning to Nigeria from his first stint of medical leave on March 10, diplomats and government sources said at the time.

Although Buhari wrote to lawmakers on Monday to confirm his return from another three months of medical leave and resumption of duties, Wednesday's cabinet meeting was cancelled without explanation.

"The president is fine, that's why he is back," a presidency spokesman told Reuters, declining to comment on why Nigeria's leader was working from home.

Instead of chairing the cabinet meeting, the first since his return, Buhari received Vice President Yemi Osinbajo, who assumed the leader's duties during his time away.

Osinbajo presented the findings of corruption investigations into two of Buhari's top officials: Secretary to the Government of the Federation Babachir Lawal, Nigeria's most senior civil servant, and Director-General of the National Intelligence Agency Ayo Oke.

"The President has to look at the report, study it and then make his own decisions based on that report," Osinbajo said.

Buhari has positioned himself as an anti-corruption crusader since his election in 2015, but in the more than two years since his inauguration, his administration has yet to dismiss, let alone convict, any major figures for graft.

On Tuesday, the heads of the armed forces briefed Buhari on security updates, the chief of defence said.

In his speech on Monday, Buhari raised concerns about an increase in attacks by Islamist insurgency Boko Haram in the northeast, ethnically-fuelled clashes through the interior and calls to violence over separatism in the southeast.

Reuters