Mike Sowe, a spokesman for the Independent Corrupt Practices Commission (ICPC), said on Thursday that investigators had identified a French agent of the firm, SAGEM SA, who had sent bribes to top officials through a Nigerian intermediary.

Those under investigation include two former interior ministers during President Olusegun Obasanjo's first term in office, a former state governor and the current permanent secretary in the interior ministry.

The announcement came on the eve of the Commonwealth summit, which will be held in Nigeria, and at a time when Obasanjo is trying to re-establish his battered anti-corruption credentials.

'Colossal sums'

An ICPC statement said that the officials are "alleged to have collected colossal sums of money" but did not put a figure on the sum.

In addition to the seven suspects living in Nigeria - who have been arrested, questioned and released pending further investigation - an eighth suspect has been detained in Britain, the statement said.

"Efforts are being made to repatriate him to Nigeria to assist the commission in its investigations," it said.

SAGEM, a French electronics and communications giant, was awarded a $214-million contract in 2001 to revive a long-standing plan to issue ID cards to the 126 million inhabitants of Africa's most populous nation.

Second most corrupt

"It was however discovered that SAGEM agents in Nigeria including Regional Area Manager Identification Systems Mr Jean Pierre Delarue, a Frenchman, and Mr Niyi Adelagun organised and executed a scheme through which bribes were distributed to these top government officials," Sowe's statement said.

Britain's Queen Elizabeth (L) on her first post-independence visit

"All the arrested officials have made useful statements to the commission, while accounts of most of the suspects in United Kingdom are being investigated," it said.

Nigeria has a notorious reputation for high-level graft. It was rated the world's second most corrupt country in this year's survey by watchdog Transparency International.

But Obasanjo, who was re-elected in April after making little impact on the problem in his first four year term, has vowed to crack down on official corruption.

On Thursday Queen Elizabeth II of Britain, who is visiting Nigeria for the Commonwealth summit, commended Nigeria's return to elected rule and urged it to move forward with plans for economic and political reform.

It is the UK monarch's first visit to the former British colony since it gained independence from her rule in 1956.