UK PM's Parliament suspension is unlawful abuse of power: SC

British Prime Minister Boris Johnson's motive for proroguing the Commons for five weeks was to avoid the risk of MPs "frustrating or damaging" his Brexit plans and "to silence Parliament for that period", the Supreme Court heard on Tuesday.

The country's highest judicial body were hearing appeals from two separate challenges brought in England and Scotland to the prorogation of Parliament in London.

Johnson's extended suspension of debate was carried out for an "improper purpose" in order to "avoid the risk of Parliament undermining the policies of his executive", said Lord Pannick QC, who was representing the businesswoman and legal campaigner Gina Miller.

Before the arguments formally began in central London, Lady Hale, the President of the Supreme Court, stressed the landmark case would have no bearing on the timing of Brexit, the BBC reported.

In her opening statement, the most senior judge in the UK said that she and her 10 colleagues would endeavour to address the "serious and difficult questions of law" raised by the case.

But she said the court would not determine "wider political questions" relating to the Brexit process and its ruling would have no bearing on "when and how the UK leaves the EU".

As the hearing went underway, some 40 protesters, holding signs reading "Defend democracy", "Reopen Parliament", "They misled the Queen", gathered outside the top court.

Over the next three days, the 11 judges of the Supreme Court will consider the two legal challenges over whether Johnson acted lawfully in advising the Queen to prorogue Parliament.