The Archbishop of Canterbury has condemned the government's Illegal Migration Bill as "morally unacceptable" and "politically impractical".

In a speech in the House of Lords on Wednesday, Archbishop Justin Welby agreed that illegal boat crossings needed to stop but said that the proposals in the Bill would cause "great damage" to Britain's reputation. 

"I urge the Government to reconsider much of the Bill, which fails to live up to our history, our moral responsibility and our political and international interests," he said. 

Under the proposals contained in the Bill, the government wants to send illegal immigrants back to their own country or to a "safe" third country like Rwanda. 

Archbishop Welby, who plans to table amendments to the Bill, said that different legislation was needed to stop Channel crossings.

"We need a Bill to reform migration," he said. 

"We need a Bill to stop the boats. We need a Bill to destroy the evil tribe of traffickers. The tragedy is that, without much change, this is not that Bill.

"This Bill fails utterly to take a long-term and strategic view of the challenges of migration and undermines international co-operation, rather than taking an opportunity for the UK to show leadership."

He was supported in his position by the Bishop of Durham, Paul Butler, who raised concerns about the detention of children.

"I am reminded of Jesus's words: 'It would be better to have a millstone around the neck and be cast into the sea than to cause a little one to stumble.' This responsibility needs to bear upon us heavily," he said. 

Tory peers took a different view, with Lord Forsyth of Drumlean responding to the Archbishop during the debate: "People are drowning in the English Channel now.

"People are leaving a safe country in order to come here and it is fatuous to try to present this as in the way that many have done."

Lord Dobbs said, "How do we stop those who arrive here claiming to be children, with stubble on their chins, who have deliberately destroyed all their documentation and paid thousands of pounds to people traffickers, enabling them to continue their awful trade?

"These people—these pretenders, if you will—are the enemies of genuine refugees, because they help to create and sustain an evil system that is run by criminals of the cruellest kind, who think nothing of throwing children overboard to drown in order to save their own miserable lives.

"They trade in lies and in lives. It is our moral obligation to stop them — to bring an end to the unimaginable pain of mothers and fathers watching their children drowning off our shores in the Channel. No amount of hand-wringing or bell-ringing will do that." 

Immigration Minister Robert Jenrick defended the Bill against the Archbishop's speech in an appearance on BBC Radio 4's World at One programme.

"Firstly there's nothing moral about allowing the pernicious trade of people smugglers to continue ... I disagree with him respectfully," he said.

"By bringing forward this proposal we make it clear that if you come across illegally on a small boat you will not find a route to life in the UK ... That will have a serious deterrent effect."