Police in the Maldives detained opposition leader Mohamed Nasheed on Tuesday, defying pressure from regional power India which had called for him to be free to campaign for elections.
Twenty masked policemen in riot gear arrested Nasheed at his family home in the capital Male and one of his security men was hurt in the melee, Shauna Aminath, a spokeswoman for Nasheed's Maldivian Democratic Party, said.
Police served no arrest warrant on the pro-democracy activist, who was the first freely elected president until last year, she said.
Authorities said Nasheed, 45, was taken into custody on a court order and would appear in magistrates' court on Wednesday to face abuse of power charges.
"He is not under arrest, but he has been taken into custody on a court order issued after he repeatedly evaded summonses to appear in court," presidential spokesman Masood Imad told AFP.
The abuse of power accusation stems from Nasheed ordering the arrest of a judge while president on misconduct charges.
A court officer said the case would be taken up at 04:00 pm (1030 GMT) on Wednesday.
Nasheed's detention threatens to bring more instability to the archipelago, an upmarket honeymoon destination straddling strategic shipping lanes in the Indian Ocean.
The US embassy in neighbouring Sri Lanka said it was "increasingly concerned" about developments in the Maldives, a nation of 330,000 Sunni Muslims.
"We urge all sides to remain calm, reject the use of violence, and avoid rhetoric that could increase tensions," the embassy said in a statement.
"Former President Nasheed must be accorded due process under the law regarding his pending court cases," it added.
Skirmishes erupted between government supporters and opposition activists in the capital shortly after Nasheed's arrest, but police quickly controlled the crowds.
Police spokesman Hassan Haneef said at least 10 police were hurt.
President Mohamed Waheed's brother Ali Waheed was also roughed up by angry crowds, but police intervened to save him, Haneef told AFP.
He said some arrests had been made and added "the situation is under control."
The capital has been wracked by violence and political infighting since February 2012 when Nasheed was ousted following a mutiny by security forces and protests.
The Indian government said it was "monitoring the situation closely".
"India expects due process and the rule of law would be followed," Foreign Ministry spokesman Syed Akbaruddin said in a statement in New Delhi.
"We would urge all concerned to exercise caution and restraint and not to resort to any violence or extra-constitutional means and steps which would weaken the democratic system," he added.
Nasheed believes the protests were fomented by former strongman ruler Maumoon Abdul Gayoom. The current government and Gayoom deny the accusations.
Seeking to avoid arrest, Nasheed took refuge in the Indian high commission (embassy) last month for 10 days and walked out only after an informal agreement was brokered by New Delhi under which he would be free to campaign.
Presidential elections are due September 7.
A conviction would bar him from holding office and his party says the charges against him are politically motivated.
"The last time there was a summons asking him to turn up in court, he went to the Indian high commission and subverted our legal system," presidential spokesman Imad said.
The Maldivian government denied any deal had been reached to end Nasheed's refuge in the embassy, but diplomatic sources say India sought assurances to bring an end to the standoff.
Nasheed came to power in 2008 after campaigning for decades for democracy in the Maldives, during which time he was repeatedly arrested and tortured while in police custody.