The Archbishop of Canterbury has condemned a British plan to send tens of thousands of asylum seekers to the East African country of Rwanda, saying the policy did not stand “the judgment of God”.

Delivering a sermon on Easter Sunday at Canterbury Cathedral, Justin Welby said the strategy announced last week by British Prime Minister Boris Johnson posed “serious ethical questions”.

Anyone who arrived in Britain illegally since January 1 could be relocated to Rwanda under the deal.

Johnson's government said it would help to break people-smuggling networks and stem the flow of migrants across the Channel, but it drew immediate and heavy criticism from politicians and charities.

“The details are for politics and politicians. The principle must stand the judgment of God and it cannot,” Welby said.

“It cannot carry the weight of our national responsibility as a country formed by Christian values, because subcontracting out our responsibilities, even to a country that seeks to do well like Rwanda, is the opposite of the nature of God who himself took responsibility for our failures,” he said.

Welby is the spiritual leader of the worldwide Anglican Communion of about 85 million Christians.

Last year, more than 28,000 migrants and refugees made the crossing from mainland Europe to Britain.

The arrival of migrants on rickety boats has been a source of tension between France and Britain, especially after 27 migrants drowned when their dinghy deflated in November.

Reuters