The Maldives government has declared a state of emergency for 15 days amid a political crisis in the island nation.
The state of emergency gives security officials in the Indian Ocean state extra powers of arrest, reports say.
The government has already suspended parliament and ordered the army to resist any moves by the Supreme Court to impeach President Abdulla Yameen.
Security forces have entered the Supreme Court and Maumoon Abdul Gayoom, the ex-president, has been arrested.
There were judges inside the court but a court spokesman said he was unable to contact them.
The US National Security Council has warned in a tweet that “the world is watching” the Maldives.
Why are all eyes on the court?
In a landmark decision on Friday, it ruled that the 2015 trial of former President Mohamed Nasheed had been unconstitutional.
Mr Nasheed, the island nation’s first democratically elected leader, was convicted under anti-terrorism laws of ordering the arrest of a judge and sentenced to 13 years in prison.
However the verdict was internationally condemned and he was given political asylum in the UK the following year after being allowed to travel there for medical treatment.
The Supreme Court also ordered the reinstatement of 12 MPs, which would see the opposition’s parliamentary majority restored.
How important is Mr Gayoom?
Now aged 80, he ruled the country autocratically for three decades before the Maldives became a multi-party democracy in 2008.
A half-brother of President Yameen, he has now aligned himself with the opposition.
He was detained in a police raid on his home, the opposition says. Shortly before, he tweeted about a large police presence outside.
How else has the government responded to the court ruling?
It sacked the police commissioner for pledging to enforce the ruling and ordered the detention of two opposition MPs who had returned to the Maldives.
It also warned that any court order to arrest President Yameen for not complying with the Supreme Court ruling would be illegal.
The Maldives previously declared a state of emergency in November 2015, after the government said it was investigating a plot to assassinate Mr Yameen.
That move came two days before a planned protest by Mr Nasheed’s Maldivian Democratic Party.
How have the opposition reacted?
Mr Nasheed, who is in exile in Sri Lanka, told BBC News that the government’s “brazenly illegal” actions amounted to a coup.
“Maldivians have had enough of this criminal and illegal regime,” he said. “President Yameen should resign immediately.”
An opposition MP, Eva Abdulla, said the state of emergency was a “desperate move” that showed the government had “lost everything [including the] confidence of the people and institutions”.
What is the Maldives better known for?
Breathtakingly beautiful beaches and breathtakingly expensive luxury hotels, says the BBC’s South Asia correspondent Justin Rowlatt.
The nation is made up of 26 coral atolls and 1,192 individual islands.
But while the water of the coral reefs that surround them may be crystal clear, politics in the “island paradise” has always been very murky indeed, our correspondent adds.
Since President Yameen took power in 2013 it has faced questions over freedom of speech, the detention of opponents and the independence of the judiciary.