Pope Leo XIV has spoken to Vladimir Putin by telephone from his hospital bed, just days after undergoing lung cancer surgery, to press for a local ceasefire in a Russian-occupied Ukrainian city.

The Vatican said the pope expressed "deep concern" about the "grave humanitarian situation" in Oleshky, in the Kherson region, where Ukrainian authorities say around 2,000 civilians remain with supply routes for food and medicine blocked.

Leo called for a local ceasefire to allow civilians to be safely evacuated and aid to be delivered. The Kremlin said Putin "supported" the Vatican's intention to help alleviate the situation.

A call from the ward

The conversation, only the second between Leo and Putin since the American pope's election, is the clearest sign yet that the 71-year-old is returning to work after Tuesday's operation at Rome's Gemelli Hospital.

The pope had the lower lobe of his right lung removed after being diagnosed with pulmonary adenocarcinoma, the most common form of lung cancer. Doctors said a chest X-ray showed "a good recovery of the operated lung" and that the post-operative course was progressing as expected.

On Friday, Leo celebrated Mass at midday in a makeshift chapel on the hospital's tenth floor, with off-duty medical and nursing staff present. Photographs released by the Vatican showed him standing at the altar. He thanked staff for their work caring for him and other patients during his homily.

He has also resumed governing the Church, accepting the resignation of an archbishop and meeting the Vatican's substitute secretary of state, Paolo Rudelli, at the hospital.

The Oleshky appeal

Ukraine has accused Russia of "deliberately creating a humanitarian catastrophe" in Oleshky, where conditions for the remaining civilians are reported to be dire. Ukrainians have appealed directly to the pope for help.

Cardinal Pietro Parolin, the Holy See's secretary of state, told reporters he hoped Putin would act on the pope's requests. "I hope that faced with a request from the Holy Father, President Putin agrees to implement what the Pope asked of him," he said.

The Vatican has sought to maintain channels to Moscow throughout the war, positioning itself as a potential mediator while repeatedly calling for humanitarian relief and peace.

A papacy reshaped

The diagnosis has nonetheless cast a shadow over a pontificate less than two years old. Archbishop Paul Gallagher, the Vatican's foreign minister, told the BBC the news was "a bit of a game changer", admitting that church figures may have taken the previously sporty and apparently vigorous pope "a little bit for granted".

"Pope Leo comes along and he's sporty and he seems to be in excellent health, and now we're told that he's not in excellent health and things have got to be sorted out," the archbishop said.

The Vatican has said the pope intends to proceed with a planned trip to South America, and further tests will determine whether he is cancer-free or requires additional treatment.

Catholics around the world were asked to pray for the pope's recovery on Saturday, as part of an International Missionary Rosary held on the eve of the 100th World Mission Day.

That the pope chose to spend one of his first acts back at work on a call to the Kremlin underlines the priority he places on the war in Ukraine – and his determination that illness will not silence his intervention.