The pandemic has put new strains on the unity of the 27-member bloc, again exposing splits between the richer north and the poorer south.

"In these times in which we need so much unity among us, among nations, let us pray today for Europe," Francis said at the start of his daily morning Mass, which he dedicates each day to a different theme related to the global crisis.

He asked for prayers "so that Europe manages to have this unity, this fraternal unity of which the founding fathers of the European Union dreamed".

It was the second time in 10 days that Francis, a big supporter of the EU, had expressed concern about the bloc. On Easter Sunday he warned that it risked collapse if it did not agree on how to recover together.

The EU's fiscally conservative northern nations remain keen to keep a tight rein on spending and have rejected calls from the ailing southern states for a joint debt - or 'coronabonds' - to fund the recovery.

EU states - whose leaders are holding a video summit on Thursday - have clashed repeatedly over financial responses to the epidemic, on issues from sharing medical equipment to cushioning the immediate economic hit.

The bloc has relaxed state aid rules and limits on public spending as well as unlocking a half-a-trillion euro rescue plan.

But Rome, Madrid, Paris, Lisbon and others believe that is not enough and call for more solidarity, casting the challenge as an existential choice for the EU.