A jogger passes The Palace of Westminster as he runs along south bank of the River Thames in London on December 24, 2020. (Photo: AFP)

LONDON, Dec. 30 (Xinhua) -- British lawmakers on Wednesday embarked on a marathon session in the British Parliament to pass into law an historic bill approving a post-Brexit trade deal agreed with the European Union (EU).

Although some politicians complained about the short length of time made available for a parliamentary debate, local media reported that the bill is guaranteed success as the legislation navigates its process through both the House of Commons (lower house of the British Parliament) and the House of Lords (upper house) in just one day.

Britain's Queen Elizabeth II is expected to give Royal Assent, almost certainly close to midnight, as soon as the bill has cleared its journey in the parliament.

British Prime Minister Boris Johnson was given a major boost for the pass of the bill as the main opposition Labour Party has announced to support the deal.

Although Britain ended its membership of the EU on Jan. 31, 2020, it has followed EU rules during a transition period which expires at 2300 GMT on Thursday. Without this new bill, Britain would enter 2021 with no trade deal with the EU.

Opening the debate in the House of Commons, Johnson told MPs: "We now seize the moment to forge a fantastic new relationship with our European neighbors, based on free trade and friendly cooperation."

"In less than 48 hours, we will leave the EU single market and the customs union, as we promised and yet British exporters will not face a sudden thicket of trade barriers, but rather, for the first time in the history of EU agreements, zero tariffs and zero quotas," said Johnson.

"The central purpose of this bill is to accomplish something that the British people always knew in their hearts could be done, but which we were continually told was impossible," he said.

The trade deal, which came after nine months of arduous negotiations between Britain and the EU, is the biggest bilateral trade deal signed by either side, covering trade worth around 668 billion pounds (about 905.4 billion U.S. dollars).

The EU is Britain's largest trading partner. Britain is the EU's third largest trading partner in goods, following the United States and China.