ABUJA (Reuters) - Nigerian President Muhammadu Buhari returned home on Saturday from three months of medical leave in Britain where he received treatment for an unspecified ailment.

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’s leave, which began on May 7 and was his second this year, left many in Nigeria questioning whether he was well enough to run the country. The refusal of officials to disclose the nature of the ailment has led to speculation about the illness.

Dressed in a dark kaftan and Muslim prayer hat, the 74-year-old Buhari walked unaided from his plane - holding rails on either side of him - after it landed at the international airport in the capital, Abuja.

He was greeted by Vice President Yemi Osinbajo, who has acted as interim leader, and was accorded a military salute. He made no statement and immediately traveled to the presidential villa.

Buhari, who took office in May 2015, handed over power to Osinbajo in his absence to allay concerns of a void at the helm of Africa’s biggest economy.

“President Buhari is expected to speak to Nigerians in a broadcast by 7 a.m (0600 GMT) on Monday, Aug. 21,” his spokesman, Femi Adesina, said in a statement on Saturday.

Buhari’s absence sparked numerous protests, including demands that Buhari should resign, as well as calls for more transparency about the president’s condition.

The All Progressives Congress (APC), the party of president and his deputy, praised the vice president’s contribution.

In a statement, it said Osinbajo had delivered “competent leadership in the absence of President Buhari and especially commends him for his effort to unite the country and drive the recovery of the national economy”.

Osinbajo’s actions included overseeing the creation of a market-determined foreign exchange window that helped push share prices to near three-year highs.

He also announced the legalizing of illicit refineries in the Niger Delta, the OPEC member’s restive southern oil hub.

The move calmed tensions and prompted regional leaders to abandon a threat to pull out of talks with the government aimed at maintaining the peace that has this year halted attacks on energy facilities which in 2016 cut oil production by more than a third.

The medical leave was Buhari’s second break for treatment in Britain this year after a spell of two months from January.

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

Little was seen of Buhari during his second stint in London. The first photograph of him was released on July 23, nearly 80 days after he left.

The frequency of images released increased in the last few weeks with Buhari appearing in photographs with visiting Nigerian state governors, the archbishop of Canterbury and the OPEC secretary general.