IBADAN, Nigeria (Reuters) -- A Nigerian state governor was impeached on Thursday after a violent power struggle with his estranged patron -- one of several political rivalries that are heating up ahead of 2007 elections.

The house of assembly of southwestern Oyo state voted to impeach Governor Rasheed Ladoja, thus removing his immunity from prosecution, over what some lawmakers alleged was gross misconduct including embezzlement of public funds.

"Governor Ladoja has today been impeached, having been found guilty of allegations leveled against him," said Olu Oyeleye, leader of a group of 18 state lawmakers who voted in favor of impeachment. There are 32 in total.

The problem in Oyo is part of a wider pattern of ruthless jostling for position ahead of 2007, when the states are due to elect their governors, who hold wide-ranging powers over state finances and security services. -------Ladoja denies wrongdoing

Ladoja denies any wrongdoing and says the 18 were bribed or otherwise influenced by Lamidi Adedibu, his former sponsor or "godfather" in Nigerian political jargon.

Several people have been killed in the past two years as Adedibu tried to unseat Ladoja, and in recent weeks supporters of the two men have fought with guns and knives, including inside the state house of assembly.

Police patrolled the streets of Ibadan on Thursday to keep the peace while the impeachment vote took place.

As is the case in many of Nigeria's 36 states, the Oyo godfather was the real power behind the governor.

Ladoja won the 2003 state election thanks to Adedibu's backing but the two fell out shortly afterwards when the governor resisted some of his patron's demands, observers in the state capital Ibadan say.

Both are members of the ruling People's Democratic Party (PDP), whose chairman said last week the governor should obey his godfather.

Analysts say the PDP has sided with Adedibu because he can help the party win the state election in 2007.

"Looking to 2007, Adedibu would serve the purposes of the PDP better than the governor. They are just being pragmatic," said political columnist Pini Jason.

He said Oyo had traditionally been a power base for a rival political alliance and it was thanks to Adedibu's strong-arm tactics that the PDP won the 2003 election.

The PDP is mainly an election-winning machine and has little political ideology.

Ruled by military dictators for most of its history since independence in 1960, Nigeria returned to civilian government in 1999 but violence, including organized thuggery and assassinations, remains a feature of political life.