"I have to confess to you that during this trip I felt a lot more tired than during other ones," the 84-year-old told reporters on the plane returning to Rome.

Francis added, however, that he did not know whether his papal voyages would slow down.

Over the past two months, the pope had to cancel some events because of sciatica -- nerve pain that means he often walks with a slight limp.

After several early morning starts and domestic flights, the pontiff appeared to have more trouble walking than usual.

Francis had insisted on making the trip to Iraq -- the first by a pope -- after 14 months of not travelling overseas because of coronavirus restrictions.

In preparation, the leader of the world's 1.3 billion Catholics was vaccinated, as were all members of his entourage.

- 'Conscious of risks' -

Francis arrived in Iraq just as the country was hit by a new surge in infections, and his visit led crowds to assemble in several churches and a stadium.

Asked about the potential danger to Iraqis posed by his visit, the pope said he took the decision to go "conscious of the risks".

"I thought about it a lot, I prayed a lot over it. And in the end, I made the decision, freely, with an inner call," he said.

On the plane, Francis said he would go to Budapest in September and mentioned possible trips to Slovakia and Lebanon.

He said he would attend the closing Mass of the International Eucharistic Congress in Budapest, an event scheduled for September 5-12.

Since the city "is two hours' drive from Bratislava, why not pay a visit to the Slovaks," he asked.

As for Lebanon, engulfed in a triple economic, health and political crisis, Francis said he wanted to go as soon as possible to a country that was "suffering".