Nigerian civil-rights group leaders are urging President Muhammadu Buhari to take a second medical leave while his health prevents him from performing his duties.

Buhari has missed the last weekly cabinet meetings, and the presidency said April 28 that he is resting and working from home. The 74-year-old leader stayed in the U.K. for more than seven weeks earlier this year to receive treatment for an undisclosed ailment, triggering speculation about the severity of his condition. He returned to Nigeria on March 10, but the presidency said in April he was expected to fly back to London for further care.

Buhari’s absence from official meetings and Muslim prayers on Friday has “fueled speculation and rumors,” the leaders of the groups said. “We are compelled to advise him to heed the advice of his personal physicians by taking a rest to attend to his health without further delay.”

Instead of briefing the public on Buhari’s health, government officials have continued to downplay his condition, the groups said. Presidential spokesman Garba Shehu said he had no comment on the statement.

The presidency said last week in a statement that Buhari was recovering and that there was no cause for concern about his health.