Pope Leo sets off on Saturday for Angola on the third leg of his four-nation Africa tour, during which he has taken on a new forceful speaking style.

Leo, who has been attacked repeatedly by President Donald Trump this week after the pope criticized the Iran war, will arrive from Cameroon, where on Thursday he said the world was "being ravaged by a handful of tyrants".

The first US pope was due to arrive in Luanda, Angola's capital, around 3p.m. (1400 GMT).

Before leaving Cameroon, Leo celebrated a farewell Mass in the capital, Yaounde, urging participants not to lose hope despite the challenges faced by the Central African country, which include a simmering conflict in its two anglophone regions that has killed thousands.

Meet President Lourenço

In Angola later on Saturday, the pope was due to meet President João Lourenço before addressing the country's political leaders.

Angola is one of the leading oil-producing nations in sub-Saharan Africa, with the sector accounting for some 95% of its exports. More than half of the country identifies as Catholic.

Leo, originally from Chicago, kept a relatively low profile for a pope in his first 10 months, but in recent weeks has become outspoken on a range of issues. He has issued sharp denunciations of war and inequality on the ambitious, 10-day Africa tour.

Crowds greeting the pope on his visit to Cameroon were enthusiastic, including an estimated 120,000 people who attended a Mass on Friday in Douala, lining the streets along his routes and wearing colourful fabrics featuring images of his face.