Former Kaduna State Governor, Nasir El-Rufai, has spent eight days in detention.
He voluntarily reported to the Economic and Financial Crimes Commission on February 16.
EFCC questioned him and later transferred him to the Independent Corrupt Practices and Other Related Offences Commission.
His lawyers say ICPC has not granted bail or shown a remand order.
They argue the legal 48-hour detention limit has expired.
Meanwhile, courts will hear two cases involving El-Rufai this week.
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A fundamental rights suit comes up on February 25.
The case seeks his release on bail.
He will also face arraignment on charges filed by the Department of State Services.
Earlier, ICPC searched his Abuja home on February 19.
His lawyers challenged the search warrant as defective and unlawful.
They asked a Federal High Court to declare the search invalid.
They also want seized items excluded from any future trial.
Before detention, officials seized El-Rufai’s passport at the airport.
His lawyers described the seizure as illegal and unexplained.
They also complained of restricted family and legal access.
They reported he suffered a nosebleed while in custody.
El-Rufai returned to Nigeria on February 12.
Authorities have not publicly explained the prolonged detention.
