Nigeria's president, Olusegun Obasanjo, was elected in 1999, promising to rid his country of rampant graft after decades of military rule. But, six years on, several state governors, the vice president, and Mr. Obasanjo himself are all being targeted in corruption investigations, and many Nigerians say little has changed.

Federal investigators in the United States last month raided the Washington-area home of Nigerian Vice President Atiku Abubakar as part of an investigation into the business dealings of a U.S. rested a prominent state governor in what Nigerian newspapers say is a money laundering investigation.

Nigeria's president, Olusegun Obasanjo, who has made the fight against graft a key tenant of his administration's domestic policy, has now agreed to be investigated by Nigeria's financial crimes commission.

All three men deny any wrongdoing. But the recent highly publicized cases have raised questions among many in Nigeria over the state of the country's war on corruption.

Mr. Obasanjo was elected president six years ago on a campaign that promised to stamp out graft. His predecessor, the late military ruler Sani Abacha, is accused of stealing more than $2 billion from government coffers during five years in power.

The creation of the national Financial Crimes Commission after President Obasanjo's election was considered by many, including the national coordinator of Nigeria's Zero Corruption Coalition, Lillian Ekeanyawu, as an important step forward.

"It was perceived with a lot of hope," she said. "It was perceived with quite a lot of hope, because Nigerians really wanted to do something about this corruption. And the expectation was high, when that announcement was made."

Although the commission has brought several investigations against leading politicians and public officials, it has yet to make a high profile conviction. That has many people, including Ms. Ekeanyawu, doubting the sincerity of those in government who claim to support its efforts.

"Nothing has changed really, if you're talking about the prevalence of corruption," she said. "There is not yet a strong enough political will."

And some, like Lagos-based journalist Lancelot Olusegun, believe the commission is being manipulated, as politicians begin to position themselves for presidential elections set for 2007.

"I tend to agree with some critics who say that the president only goes after those he perceives are his political enemies, and that those in his camp, no matter what they do, do not get prosecuted," said Lancelot Olusegun.

President Obasanjo is being investigated for allegedly taking kickbacks on oil contracts and holding illegal bank accounts abroad. He denies any wrongdoing. His accuser is Abia state Governor Orji Uzor Kalu, a member of the president's ruling Peoples Democratic Party, who has become one of his most vocal critics.

Mr. Kalu, who says he plans to run for president, is also under investigation by the commission on similar charges, including holding illegal foreign bank accounts. He also denies wrongdoing.

Nigeria's constitution grants certain high-level government officials immunity from criminal prosecution while in office. The original intention had been to allow them a free hand to govern.

Journalist Lancelot Olusegun says the immunity clause needs to be changed.

"Immunity should not just cover everything," he said. "If there is evidence to show that the president or the governors have committed fraud crimes, it should be investigated and brought to trial."

The existence of the immunity clause means it is unclear whether the investigations of either President Obasanjo or Governor Kalu could lead to criminal prosecution.