Presidency sources initially said their principal will return last Saturday, but that was not the case.
The report claims Buhari’s doctors have to carry out a test on him on Monday and the results will determine when he will return to Nigeria.
His wife, Aisha, travelled to the UK on May 30 to see the President, who has been out of the country since May 7 for further medical check-ups.
“My husband is recovering fast. And very soon, he will return to the country to resume his official duties,” she said on arrival.
Officials have refused to disclose details of his health condition.