El Salvador is conducting mass trials of thousands of suspected gang members, many of whom have spent years in prison without charge or visiting rights, as part of iron-fisted President Nayib Bukele's anti-gang crackdown.

After three days in Angola, the US-born pontiff is due around noon (1100 GMT) in the Central African country, ruled since 1979 by Teodoro Obiang Nguema Mbasogo, 83, the world's longest-serving head of state who is not a monarch.