Pope Francis remained in critical condition Monday but showed slight improvement in laboratory tests and resumed some work, the Vatican said, including calling a parish in Gaza City that he has kept in touch with since the war there began.

Officials said Pope Francis is in critical condition as he battles pneumonia and early kidney failure. He was awake and eating normally during his treatments. Crowds have been gathering at Vatican City to pray for his recovery. Doctors reported Sunday that blood tests showed his early kidney failure was under control.

The kidney ailment appears to be in an early stage, the Vatican said, adding that the pontiff is still receiving high flows of oxygen for his respiratory illness.