The 89-year-old, who is a conservative Catholic, has been subject to a European Union travel ban since 2002 following allegations of election rigging and human rights abuses.

However, he is able to travel to the Vatican, which is technically a state within a state and not part of the EU, although any visitor must pass through Italian territory.

Pope Francis will be officially installed as the new leader of the Roman Catholic Church on Tuesday, the Vatican said last week. A papal inaugural mass is customarily attended by heads of state and governments.

Mugabe, who has ruled the southern African country since independence from Britain in 1980, was expected to leave for Rome late on Sunday, a day after Zimbabweans voted in a referendum expected to endorse a new constitution that would curb presidential powers.

Mugabe last visited the Vatican in April 2011 when he joined world dignitaries for the beatification of Pope John Paul.

He has staunchly opposed gay rights that he says are immoral and not compatible with African cultural practices in Zimbabwe.