Nigeria's president declared a state of emergency Thursday in a troubled southwest state where he said the impeachment of the governor by the local legislature violated the constitution.

Legislators in southwest Ekiti state voted to remove Gov. Ayo Fayose on Monday after finding him guilty of siphoning state funds into personal bank accounts and receiving kickbacks.

"I hereby declare a state of emergency in Ekiti state," President Olusegun Obasanjo said in a national broadcast.

He suspended the state legislature for six months, along with Fayose, his deputy and Friday Aderemi, the former speaker of local parliament who is claiming to be governor.

Obasanjo appointed a retired general to administer the affairs of the state and maintain security there for the next six months.

The removal of Fayose was illegal because some steps in the impeachment process violated Nigeria's constitution, Obasanjo said.

CountryWatch: Nigeria

Information Minister Frank Nweke said the legislators' removal of a state chief judge was an action outside their power. The replacement judge set up the impeachment panel that found Fayose guilty of misconduct.

"It is a clear case of usurpation of power," Obasanjo said of the impeachment of Fayose. "It is dangerous for our democracy to allow this flagrant violation."

Troops and police were patrolling the streets of Ado Akiti, the state capital, and guarding key government buildings, residents said.

Meanwhile, rival governments had set up in different neighborhoods. The former speaker of the legislature chose a Cabinet in one part of the city. In another neighborhood, Fayose's deputy held a Cabinet meeting on behalf of the deposed governor.

Fayose has remained in hiding since being ousted. Deputy Gov. Abodun Olujimi was also fired by the legislature for alleged complicity in the crimes.

The stream of allegations and office shuffling add to growing uncertainty about the stability of Africa's most populous country ahead of crucial general elections due in April 2007.

Thirty-one of Nigeria's 36 state governors are being investigated for corruption, according to the country's financial crimes agency. Nigeria is regularly rated among the most corrupt countries in the world by Berlin-based anti-graft watchdog Transparency International.

Click here to go to FOXNews.com's Africa Center.

Obasanjo himself has been accused of misusing state funds by his vice president, who plans to run for the presidency when Obasanjo's final term runs out next year. The relationship disintegrated after a failed move by Obasanjo's supporters to amend the constitution so he could run again; Vice President Atiku Abubakar opposed the proposed change.

The president has accused his deputy of corruption and Abubakar's membership of the ruling party has been suspended.

Nigeria is Africa's largest oil producer and the fifth-largest supplier of oil to the United States. Much of the oil proceeds never reach the poor in the regions where the crude is pumped.