COLOMBO (AFP) - Security was stepped up outside Sri Lanka's top court on Friday (Dec 7) ahead of an expected ruling on whether the President broke the law by sacking Parliament last month, a decision that could potentially lead to impeachment proceedings.

President Maithripala Sirisena plunged the country into crisis on Oct 26 when he fired the prime minister and appointed the contentious Mr Mahinda Rajapaksa in his place. He then dissolved Parliament on Nov 9.

Four days later, the Supreme Court issued an interim ruling suspending Mr Sirisena's decree and restoring Parliament, which almost immediately passed a no-confidence motion against Mr Rajapaksa.

The court's seven-judge bench was likely to deliver a final ruling on the constitutionality of Mr Sirisena's move on Friday.

"If the morning session is brief, we can expect a decision later today," a court official said.

Sacked premier Ranil Wickremesinghe's party and its allies, who command a majority in the 225-member assembly, have suggested that they could begin impeachment proceedings against Mr Sirisena, depending on the ruling.

Mr Wickremesinghe's party loyalists believe that the court decision will go in their favour, a view held by many independent lawyers.

Problems for Mr Sirisena were compounded on Monday when the Court of Appeal suspended the entire Cabinet and asked Mr Rajapaksa to explain on what authority he was holding office.

With parliamentary proceedings degenerating into brawls, the United States, the European Union and other powers have raised concerns over the crisis in the strategically important island nation of 21 million people.

Only China has recognised the appointment of Mr Rajapaksa, who during his decade as president until 2015 relied heavily on Beijing for diplomatic and financial support.

As president from 2005 until 2015, he ended Sri Lanka's four-decade civil war by crushing the rebel Tamil Tigers in 2009.

But 40,000 ethnic Tamils were allegedly massacred in the process. Mr Rajapaksa and his family are also alleged to have profited from his time in power through corrupt deals.

During an earlier stint as prime minister from 2001 until 2004, Mr Wickremesinghe is credited with pulling Sri Lanka out of its first ever recession, in part with reforms that have endeared him to the West.