A pigeon is seen near placards demanding extension of Brexit transition period outside the Houses of Parliament in London, Britain, on June 10, 2020. Britain will not extend its transitional links to the European Union (EU) beyond Dec. 31, a government minister said Tuesday following the stalled talks between London and Brussels last week. (Photo by Tim Ireland/Xinhua)

British lawmakers on Monday backed a new bill that would override parts of the Brexit treaty struck with the European Union (EU) in 2019, despite outrage in Brussels and alarm at home over such an overt breach of international law.

MPs in the House of Commons gave their initial approval to the UK Internal Market Bill by 340 votes to 263, clearing the way for four days of detailed scrutiny of the text this week and next.

British Prime Minister Boris Johnson earlier argued the legislation was a "safety net" against what he claimed were EU threats to impose tariffs on UK internal trade and even stop food going from mainland Britain to Northern Ireland.

But EU leaders have dismissed this as "spin" and warned Johnson to uphold commitments he himself made in the Brexit treaty in 2019 - demanding he withdraw the offending parts of the new bill by the end of September.

The row threatens to disrupt already tough post-Brexit trade negotiations, fueling growing fears of failure that would see more than four decades of EU-UK integration come to a crashing halt at the end of 2020.

The legislation also sparked angry debate in London, reminiscent of the years of bitter political battles that followed the 2016 vote to leave the EU.

Several of Johnson's own Conservative MPs expressed alarm about breaking international law, with ex-finance minister Sajid Javid and former attorney general Geoffrey Cox among those saying beforehand that they would not back the bill as it stood.

Every living former prime minister - Conservatives John Major, David Cameron and Theresa May and Labour's Tony Blair and Gordon Brown - also warned of the risk to Britain's global reputation.

AFP