Nigeria’s president, Muhammadu Buhari, has said he needs more rest and health tests after returning home from nearly two months of medical leave in Britain, during which time his deputy has run the country.Shortly after arriving from London, the 74-year-old former general told officials he was feeling much better but wanted to rest over the weekend, raising questions about his ability to run Africa’s biggest economy and most populous nation. The vice-president, Yemi Osinbajo, a lawyer who is seen as more business-friendly than Buhari, played an active role in driving policy changes in Africa’s top oil producer during the president’s seven-week absence. The Nigerian stock market jumped to a one-month high when Buhari returned, but trimmed gains after his comments about his continued ill-health raised fears of policy confusion and a power vacuum. Dressed in a dark kaftan and Muslim prayer cap, Buhari walked stiffly but unaided from his plane after it landed at an airbase in the northern city of Kaduna. Facebook Twitter Pinterest Osinbajo, left, greets Buhari as he returns to Abuja. Photograph: Sunday Aghaeze/APAfter greeting a handful of provincial and military officials, he boarded a helicopter to Abuja to address Osinbajo and his top military and security commanders in a brief speech. “I deliberately came back towards the weekend so that the vice-president will continue and I will continue to rest,” Buhari said at the presidential villa. “All I need is to do further follow-ups within some weeks.” He said he was conscious of the needs of the economy, mired in its first recession in 25 years due to a collapse in oil revenues, but failed to clarify Osinbajo’s role or the extent of his powers now Buhari is back home. Buhari had formally made him acting president when he left for treatment, but that appointment can only stand when the president is out of the country. Buhari also did not reveal details of his sickness. “I couldn’t recall when last I had a blood transfusion,” he said. About his treatment in London he added: “Blood transfusions, going to the laboratories and so on and forth.”Buhari has travelled to Britain several times to consult doctors since he was elected two years ago. Officials have refused to disclose details, saying only that he underwent routine tests. This fuelled speculation that his health was worse than publicly admitted. In images released by his office on Thursday, Buhari looked painfully thin but was smiling as he greeted the archbishop of Canterbury, Justin Welby, in London. They were the first official pictures released in three weeks. Facebook Twitter Pinterest Buhari meets Welby in London. Photograph: ReutersBuhari, who first came to power in a military coup in 1983, is a northern Muslim while Osinbajo is a lawyer from Nigeria’s predominantly Christian south, a political arrangement that reflects Nigeria’s broad geographic and religious divisions. Reflecting his popularity in the north, armed police had to control hundreds of cheering supporters as Buhari’s plane landed in Kaduna. Osinbajo played a prominent and active role in Buhari’s absence, chairing cabinet meetings and finishing work on an economic reform plan needed to secure a World Bank loan to help plug a deficit caused by low oil revenues. He also travelled several times to the commercial capital, Lagos, and the Niger Delta oil hub to calm tensions with militants attacking oil facilities – two regions Buhari had largely ignored. The central bank also devalued the naira for retail customers, suggesting a wider devaluation of the currency may be in the offing despite Buhari’s entrenched opposition to such a move. The transparency over the temporary handover to Osinbajo stands in marked contrast to the secrecy and confusion that surrounded the illness of President Umaru Yar’Adua, who died in 2010 after a long period of medical treatment in Saudi Arabia.