Cardinal Robert Sarah, from Guinea, is the head of the Vatican's liturgy office

An African cardinal has branded mass migration a 'new form of slavery'.

Cardinal Robert Sarah, touted by many to succeed Pope Francis as the next pontiff, said in a new interview with French publication Valeurs Actuelles that the Church should oppose migration.

'It is a false exegesis to use the Word of God to promote migration. God never wanted these rifts,' Cardinal Robert Sarah said.

'All migrants who arrive in Europe are penniless, without work, without dignity...This is what the Church wants?' he asked.

'The Church can not cooperate with this new form of slavery that has become mass migration.'

Sarah, from Guinea, who serves as the head of the Vatican's liturgy office, added that he believed 'Islam will invade the world' if migration is not controlled.

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Robert Sarah, Archbishop of Conakry Guinea being made a cardinal by the Pope in November 2010

'If the West continues in this fatal way, there is a great risk that, due to a lack of birth, it will disappear, invaded by foreigners, just as Rome has been invaded by barbarians,' he added.

Sarah added: 'My country is predominantly Muslim. I think I know what reality I'm talking about.'

His comments put him in direct opposition to the Pope, who has previously emphasized the need for western nations to take on more migrants.

Last week, Sarah spoke in Morocco, the main destination for sub-Saharan African migrants seeking to reach Europe via Spain, and frequently mentioned migration.

'The issue of migration will never be resolved by raising barriers, fomenting fear of others or denying assistance to those who legitimately aspire to a better life for themselves and their families,' Francis said.

'If Europe disappears, and with it the invaluable values of the old continent, Islam will invade the world,' Sarah said. 'And we will totally change culture, anthropology, and moral vision.'