ROME and LONDON -- Pope Francis is "resting" on Monday morning after spending his 10th night in the hospital, the Vatican press office said.

"The night passed well, the Pope slept and is resting," the office said in a short statement.

The 88-year-old pontiff, who has led the Catholic Church since 2013, underwent another round of clinical tests on Sunday morning, Vatican sources told ABC News. Officials said Sunday he remained in critical condition.

Francis has been hospitalized at Rome's Gemelli Hospital since Feb. 14 following a bout with bronchitis. He was diagnosed with pneumonia on Tuesday, according to the Vatican.

This is a developing story. Please check back for updates.