The Archbishop of Canterbury has said a second Brexit referendum may be needed if parliament fails to agree a deal with the European Union on the terms of Britain's withdrawal.

Speaking yesterday in the House of Lords, Justin Welby said if parliament could not agree it would have shown itself 'unfit for the job'.

A no-deal Brexit would be deeply damaging, he said.

'That outcome would be not only a political and practical failure, but a moral one equally as serious as ignoring the result of the referendum entirely. A second referendum is not my preference, but if parliament fails in the task entrusted to it, then regrettably it may be required. This is about more than Brexit, and parliament must not show itself unfit for the job.'

Warning of the effects on his own Canterbury diocese, he referred to the risk of cross-Channel delays leading to thousands of lorries being held in miles-long queues.

'This will have a major impact on local towns and villagees, as we saw in Operation Stack three or four years ago.'

He called on MPs to show 'leadership', saying: 'Parliamentarians must be able to look back at this time and say honestly to the people of this country that we put them, their choices, their welfare and their communities above the politics and ideology that can seem so all-consuming here in Westminster.'

Welby's predecessor as archbishop, Rowan Williams, called yesterday for the Article 50 process – which formally commits Britain to leaving the EU on March 29 – to be revoked. Interviewed for the BBC's Newsnight programme, he said: ' 'Personally, I would like to see that.' He said: 'That's not to prejudge how the referendum result is activated but I would say we cannot arrive at a reasoned sensible conclusion with the timetable we have got.

'With the clock ticking so audibly at the moment, we are approaching a very dangerous cliff edge. I think we need more time.'