ABUJA (Reuters) - Nigeria’s President Muhammadu Buhari will return to his official duties as soon as doctors advise that he can end his medical leave, according to a statement from the presidency on Tuesday.

FILE PHOTO: Nigerian President Muhammadu Buhari speaks at the United Nations General Assembly, U.S., September 20, 2016. REUTERS/Kevin Lamarque/File Photo

He left the capital, Abuja, for London on May 7.

“I am making good progress, and as soon as doctors advise, I shall return to my duties and continue serving the Nigerian people who elected me and are daily praying for my recovery,” Buhari said in a letter to Guinea President Alpha Conde, dated July 24, according to the presidency statement.

Amid conflicting reports on the 74-year-old’s health, his office released a photograph on Sunday - the first for almost three months - showing a smiling Buhari looking less gaunt than when he was last seen on television in Nigeria.

The picture purported to show Buhari dining in Britain with senior members of his political party, according to an accompanying statement from the presidency.

In Abuja, his spokesman announced that seven state governors, including two from the opposition People’s Democratic Party (PDP), would visit Buhari in London on Wednesday.

“It is a goodwill visit to the president by the governors,” Garba Shehu told journalists.

Buhari has been abroad twice this year for health reasons. The first trip, also to London, lasted nearly two months and a number of photographs of him were published.

Buhari, a former military ruler who took office in May 2015, handed over to his deputy, Yemi Osinbajo, to allay concerns about a possible power vacuum in his absence.

With the economy in recession, Nigerian authorities are also fighting an Islamist insurgency in the northeast and trying to maintain a fragile ceasefire by militants whose attacks in the Niger Delta last year cut oil production by more than a third.

The refusal of officials to disclose details of Buhari’s illness has triggered fierce speculation in Nigeria’s media and on social media over the last few months about whether he will seek a second term in the 2019 election.