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President of Nigeria Muhammadu Buhari arrives to speak at the U.S.-Africa Business Forum at the Plaza Hotel on Sept. 21, 2016 in New York City. Getty Images

Nigerian President Muhammadu Buhari has not only recovered from a recent illness that took him to London for extensive medical tests but has also returned to the daily grind.

Senate President Bukola Saraki wrote on Facebook that Buhari, 74, was "doing well, was cheerful and in good spirits" Wednesday amid mounting concern over the leader's health, AllAfrica reported. Buhari started rumors last month when he extended his 10-day vacation in the United Kingdom on the recommendation of his doctors, but his administration has continually tried to tamp down speculation about his health.

Saraki released his statement after he and a few other officials went to London this week to meet with Buhari.

"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," Saraki added. "The president I saw today is healthy, witty and himself."

House Speaker Yakubu Dogara took his reassurances to social media, as well, posting a photo on Twitter of the president. "He is fit as a fiddle," Dogara wrote.

Buhari has also apparently been working remotely. The White House confirmed Tuesday that newly sworn-in President Donald Trump spoke with his Nigerian counterpart this week about the economy, governance and national security — especially as it applies to the African nation's challenges with the Islamist extremist organization Boko Haram.

"The leaders agreed to continue close coordination and cooperation in the fight against terrorism in Nigeria and worldwide," the White House wrote in its readout of the call. "President Trump expressed support for the sale of aircraft from the United States to support Nigeria’s fight against Boko Haram."

Buhari adviser Femi Adesina tweeted Trump also invited Buhari to visit Washington, D.C., and told him the U.S. was ready to negotiate with Nigeria to forge a weapons deal aimed at fighting terrorism, Premium Times reported.