Zürcher Nachrichten - Pope clears diary for tests on painful knee

"The pope has slowed down his activities today due to medical checks that were necessary today. That's why the agenda is empty today," spokesman Matteo Bruni told reporters.

The 85-year-old pontiff had been due to meet Argentina's foreign minister, Santiago Cafiero, on Friday but the meeting was cancelled, an Argentine government official told AFP.

Francis cancelled a trip to Florence in February due to "acute" pain in his right knee, which also stopped him presiding over Ash Wednesday celebrations.

Over Easter weekend, he broke with tradition by not presiding over the Saturday celebrations at Saint Peter's Basilica.

The Argentine pope, elected in 2013, underwent surgery for an inflamed large colon last year, but is believed to be otherwise in relatively good health.

He also suffers from sciatica, a chronic nerve condition that causes, back, hip and leg pain that has occasionally forced him to cancel official events.

During a weekend trip to Malta earlier this month, the pope used a lift for reduced mobility passengers to board the plane.

He walked with difficulty throughout the trip, after which he told reporters that his knee was "a little annoying but it's getting better".

E.Schneyder--NZN