KANO, Nigeria (AFP) -- A prominent Nigerian politician whose wife was murdered in the northern city of Kano two weeks ago has warned the government over failure to prosecute her killers.

"I would like to warn the federal government and the police that they have to conclude this case and prosecute the killers," Abubakar Rimi told journalists in his first public reaction to the January 14 murder of his 43-year-old wife, Sa'adatu.

"I must also warn the government and the police that Kano is not the kind of place where this thing would happen and the government does nothing about it", added Rimi, a former presidential candidate and minister.

His wife was "gruesomely murdered", according to the police, one month after he angrily left President Olusegun Obasanjo's ruling People's Democratic Party.

Police said that a gang broke into Rimi's house in Kano shortly before dawn and killed his wife. Tens of suspects have been arrested over the murder, according to the police.

"I believe I was the target of the murderers but when they discovered I was not at home, they killed my wife in my place. For the peace of Nigeria, the government will have to see to it that the culprits are brought to book, no matter how highly placed they are in the society," said Rimi.

The police have offered a reward of five million naira (38,400 dollars / 31,700 euros) for "information that will lead to the identification and arrest of those who committed this heinous crime".

Rimi, 66, former communications minister and ex-governor of Kano State, the commercial centre of Nigeria's mainly Muslim north, married in 1959 and had two daughters and five sons.

He was a leading member of Obasanjo's party but quit last month, along with 11 other senior party figures, to join a group set up to oppose any attempt by the president to seek a third term in office.

Obasanjo is theoretically barred from seeking a third mandate, but political tensions have been mounting in recent months amid rumours that the president will seek to change the constitution.

Since the advent of the civilian regime in May 1999, there have been dozens of unexplained murders and assassinations, prominent among of which is that of Obasanjo's former justice minister Bola Ige, in December 2001.