ABUJA (Reuters) - Nigerian President Muhammadu Buhari needs further rest in Britain following medical tests but there is no need to worry about him, his spokesman said on Tuesday, as his deputy launched a 60-day plan to improve the recession-mired economy.

FILE PHOTO - Nigerian President Muhammadu Buhari speaks during German President Joachim Gauck's visit to the State House in Abuja, Nigeria February 11, 2016. REUTERS/Afolabi Sotunde/File Photo

Buhari, 74, went to London a month ago for medical tests for an unspecified illness, putting Vice President Yemi Osinbajo, 59, in charge. He had originally planned to stay 10 days.

The government has sought to allay concerns of a void at the helm of Africa’s biggest economy during a recession by stressing that Osinbajo has full powers as acting president.

“The president needs to rest for some further time,” Buhari’s spokesman Femi Adesina told reporters in Abuja. “From the results of the (medical) tests further rest has been recommended.”

He declined to say when Buhari might be back or what his condition is, saying only: “There is no cause to worry. He is the one who owns his body. There is nobody who knows his body better than him.”

Osinbajo, a lawyer, has been holding cabinet meetings and continuing work on an economic reform plan needed to secure a World Bank loan to help plug a deficit caused by low oil revenues.

The 60-day plan he launched on Tuesday aims to attract more investment to Nigeria.

“There are improvements which we expect to see at our ports. Improvements at our airports, improvements at the seaports, improvements in immigration visas,” he said in a statement, without giving details.

CURRENCY CONCERNS

The government had planned to ease the movement of goods and issuing of business visas delayed by corrupt officials but little had been approved amid inertia under Buhari.

The central bank on Monday devalued the naira for retail customers, days after a top advisory body demanded at a meeting chaired by Osinbajo an urgent review.

Buhari has rejected a devaluation despite even some officials privately saying the high naira rate had been deterring badly needed investment.

Osinbajo has also traveled during Buhari’s absence several times to the Niger Delta oil hub to discuss development projects to end attacks by militants fighting for oil revenues.

He met anti-government protesters who had marched on the presidential villa - in contrast to Buhari who has not traveled much in recent months, spending time mostly with his key aides.

Buhari’s predecessor, Goodluck Jonathan, was sworn in after the death in 2010 of President Umaru Yar’Adua. His illness created a power vacuum that was only filled by Jonathan, his vice president, after three months of political infighting.