These arrested seven suspects are obvious possibilities in the crime

Haz Iwendi, police spokesman

Police say the unidentified man told them he had been one of eight men hired to kill Mr Ige.

Mr Ige, a close friend of President Olusegun Obasanjo, was shot dead last Sunday evening at his home in Ibadan in south-western Nigeria.

Walk-in confession

Senators have held an emergency meeting in the capital, Abuja, to discuss security measures in the wake of the killing.

"We are still collating our facts from all over the federation, but these arrested seven suspects are obvious possibilities in the crime," a spokesman for the federal police, Haz Iwendi, said.

According to Oyo State Police Commissioner Mike Okuo, the man who confessed to the killing walked into the headquarters of the state police in Ibadan late on Wednesday

The man told police he took part in the killing after being promised 1,000,000 naira (about $8,500) to carry out the crime.

Remorse

"I personally interrogated him because he insisted on seeing me, and I can tell you, he gave us useful information which I have passed to the head of the investigation team," Mr Okuo said.

Mr Okuo described the man as sane, coherent and filled with remorse.

We are still continuing our investigation despite the man's confession

Haz Iwendi, police spokesman

However, Mr Iwendi said police "do not want to be distracted by his confession" and that the investigation was continuing.

"We are checking all information we receive because every piece of information is vital to us. We are still continuing our investigation despite the man's confession," he said.

No clear motive for the killing has been established, but before his death, Mr Ige had become involved in a dispute between the Osun state governor and his deputy.

Presidential pressure

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

Mr Ige, who was 71, was an influential figure in the ethnic 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".