Nigerians have reacted angrily to the arrest of a prominent news blogger by the anti-corruption agency for "offences bordering on cyber-stalking".
The Economic and Financial Crimes Commission (EFCC) had abused it powers by arresting Abubakar Sidiq Usman, the governing party’s youth wing said.
His followers have launched a #FreeAbusidiq campaign on Twitter.
Last week, Mr Usman published allegations that EFCC acting chairman Ibrahim Magu was bullying his staff.
Mr Usman is an extremely popular blogger and the opposition People’s Democratic Party (PDP) has also said it is deeply concerned about his arrest, reports the BBC’s Nasidi Yahaya from the capital, Abuja.
He is a strong backer of President Muhammadu Buhari, and a founding member of the youth wing of the governing All Progressives Congress (APC).
In a statement posted on its Facebook account, the APC youth wing said he was being held on "spurious charges".
The EFCC was formed to investigate financial crimes and had overstepped its jurisdiction by detaining him, it said.
On Monday, the EFCC said Mr Usman was being questioned for "offences bordering on cyber-stalking", and he had been offered bail.
He remains in detention and has not been charged in court.
Mr Usman is the third blogger to be arrested in Nigeria since the Cyber Crime Act came into force in 2015, a local newspaper reports.