A leading critic of Philippine President Rodrigo Duterte, Senator Leila de Lima, has been arrested on drug trafficking charges.
Senator Leila de Lima is accused of receiving money from detained drug lords.
She has insisted on her innocence and says the charges are an attempt to silence her criticism of Mr Duterte's war against drugs.
She had spent the night in the Senate in Manila to evade arrest on Thursday.
But on Friday morning she surrendered to police, telling reporters: "It is my honour to be imprisoned for the things I am fighting for.
"They will not be able to silence me and stop me from fighting for the truth and justice and against the daily killings and repression by the Duterte regime."
Ms de Lima's charges stem from events which allegedly took place when she was justice minister between 2010 and 2016.
She is accused of abetting the drug trade by extorting money from inmates in the notorious New Bilibid Prison, who in turn raised money by trafficking drugs within the jail.
Ms de Lima has been one of the most vocal critics of Mr Duterte, and previously investigated him for extra-judicial killings when Mr Duterte was mayor of the city of Davao.
Mr Duterte launched a brutal nationwide drug war in July 2016 shortly after becoming president. More than 7,000 people have been killed.Image copyright Reuters Image caption Mr Duterte has defended his controversial campaign as necessary to eradicate drug use and crime in the Philippines
Critics say the president has encouraged police, vigilantes and mercenaries to shoot suspected drug dealers and users on sight.
The death toll from the crackdown has attracted intense criticism from human rights groups and Western countries, although the president continues to enjoy a high level of support among Filipinos.
Mr Duterte has defiantly defended the crackdown, saying the country is plagued by drugs and that police were only authorised to open fire when threatened by suspects.
But the operations were suspended last month after the killing of a South Korean businessman inside police headquarters.
Mr Duterte said the police force needed to be cleaned up and has now ordered the Drug Enforcement Agency, rather than the police, to lead it, with back-up from the military.