No details were given of his alleged connection to the murder on 23 December, which shocked Nigerians.

Mr Ige's family has announced that he will be buried on Friday.

It is not known why the 71-year-old lawyer was shot dead in his bedroom by a group of armed men.

He was the most senior politician to be murdered since democratic rule returned to Nigeria in 1999.

Discarded lead

He was involved in a local political dispute in his home state of Osun, backing the governor against his deputy.

As justice minister, he strongly criticised the introduction of Sharia law in 13 states in northern Nigeria.

Ige's family will bury him on Friday

There is also speculation that his job of fighting drug traffickers may have provided the motive for his murder.

Twenty-seven people have been interrogated so far and eight are still being held, according to the police.

A man had confessed to the murder but Reuters news agency says the police have discarded that lead amid questions over his sanity.

More deaths

Police have offered a 500,000 Naira reward - about 15 times the average annual income in the country - for information leading to the killers.

Ibadan was hit by more violence over the week-end, as three people were killed in clashes between bus drivers and the ethnic Yoruba militia.

President Olusegun Obasanjo lost a close friend

The Odua People's Congress has been blamed for the fighting, which local newspapers said was sparked by an argument over a fare.

Mr Ige was an influential figure in the Yoruba community and a close friend of President Obasanjo.

The Nigerian leader has described him as "a friend, patriot, colleague, nationalist and somebody who has worked closely with me in the last two and a half years".

Mr Obasanjo said he had ordered the police to "fish out the perpetrators of this dastardly act".

Mr Ige belonged to a different political party to Mr Obasanjo and his appointment came as a surprise.