Nigerians should not be concerned with the health of their head of state, currently on medical leave in the UK, the president of the senate has said. Bukola Saraki made the statement after visiting President Muhammadu Buhari in Abuja House in west London.

"Myself, Rt Honorable Speaker Yakubu Dogara and leader of Senate, Senator Ahmed Lawan paid a visit to President Buhari in Abuja House in London. We were delighted to see that President Buhari is doing well, was cheerful and in good spirits,"Saraki said in a statement, according to the Premium Times website.

"The president's absence and imminent return shows that there is no vacuum in government and our system of democracy is working with all organs of government fulfilling their mandate."

Following the visit, the official Twitter handle of Buhari posted some pictures of the meeting.

"I thanked them for visiting. I'm also grateful to Nigerians, Christians and Muslims alike, for their prayers and kind wishes for my health," said one the posts.

Is Buhari ill?

Nigerians have become increasingly concerned with the health of their head of state, who has been on medical leave for four weeks now. The 74-year-old leader was scheduled to return to Nigeria on 6 February, but prolonged his stay to complete medical tests recommended by doctors.

The move fanned further rumours about his deteriorating health and is likely to erode confidence in his administration.

President Muhammadu Buhari in London
Nigeria's president Muhammadu Buhari announced in January he would take a 10-day-long vacation to relax and undergo a medical check-up in the UK AFP/Getty

The Nigerian presidency has released several statements dismissing allegations Buhari was gravely ill or even dead.

Nigerians have also expressed disbelief following news that Buhari had a phone conversation with his American counterpart Donald Trump.

Buhari's spokesperson Femi Adesina, who confirmed the phone call took place, described the conversation – the first since Trump assumed office in January – as "cordial". The US government also confirmed the phone call took place, but no details of the conversation were given.

It is not clear yet when Buhari is to return to Nigeria. Staff at the Abuja House refused to provide any updates on Buhari's health when IBTimes UK arrived at the government-owned building to find out more about his progress.

People have drawn similarities between Buhari's medical leave and that of deceased former president Umaru Yar'Adua, who was admitted to a hospital in Saudi Arabia in 2009.

The country experienced a power vacuum filled only when the senate approved a Doctrine of Necessity to allow the then vice-president Goodluck Jonathan to be sworn in.