Activists are accusing Nigeria's government of intimidating and harassing the judiciary after several senior judges were detained in weekend sting operations.
Nigeria's intelligence services announced more than $800,000 had been seized in raids targeting judges from the country's high courts. The State Security Service said it had been monitoring the judges' "expensive and luxurious lifestyle'' amid complaints they had accepted bribes.
It did not specify how many judges were in custody.
Civil society groups quickly cried foul. The Socio-Economic Rights and Accountability Project, an organization that previously has accused judges and lawyers of abetting corrupt officials, said it was "seriously concerned'' about the arrests and called on all judges to be released immediately.
The arrests "served to undermine the independence of the judiciary in Nigeria, and reinforce the practices under successive governments of undue political interference in the judiciary,'' the group said.
In a statement Sunday, the office of President Muhammadu Buhari said all arrests and searches were carried out according to the law in a bid to root out corruption.
"The recent surgical operation against some judicial officers is specifically targeted at corruption and not at the judiciary as an institution,'' the statement said.
Buhari, a former military dictator, won election in 2015 while promising to tackle corruption, which he has blamed for the deaths of thousands in the ongoing fight against the extremist group Boko Haram.
But the president has been accused of targeting his political enemies while ignoring corruption allegations against people in his own administration.