British Prime Minister Boris Johnson Photo: VCG

Britain's Supreme Court began considering legal challenges Tuesday to Prime Minister Boris Johnson's controversial decision to suspend parliament for over a month, as the country's political crisis over Brexit intensifies.

The court started hearing three days of arguments over Johnson's move to shutter, or prorogue, the House of Commons last week until October 14 - just two weeks before the country is scheduled to leave the European Union.

The politically-charged case, unprecedented in Britain, could lead to parliament being recalled and Johnson's political hand severely weakened in the run-up to the October 31 departure date.

The appeals revolve around "whether it was lawful for the prime minister to advise Her Majesty to order prorogation," Supreme Court President Brenda Hale said as she opened proceedings.

"This is a serious and difficult question of law.

"We are not concerned with the wider political issues.

"The determination of this legal issue will not determine when and how the UK leaves the EU."

At a small demonstration outside, protesters held up placards reading "Defend Democracy".

One was dressed as the Incredible Hulk - a reference to an analogy made by Johnson between the comic book character and Britain as it prepares to leave the EU.