ABUJA (Reuters) - Nigeria's central bank on Tuesday limited the tenure for chief executive officers at domestic financial institutions to a maximum of 10 years to prevent a repeat of last year's multi-billion dollar bank bailout.

The regulator said it would give affected banks up to July 31 to find successors to their current CEOs. It would not specify which banks would be impacted by the regulation.

"The Central Bank of Nigeria ... has issued the following guidelines to address some corporate governance issues in the deposit money banks," it said.

To avoid conflicts of interest, the regulator also prohibited top central bank officials from seeking jobs with private financial institutions for at least three years.

Central Bank Governor Lamido Sanusi has made banking reforms one of his top priorities and has imposed a series of bold measures welcomed by foreign investors.

Nigeria's central bank has injected about 600 billion naira into the banking system since mid-August and sacked senior executives after its auditors found lax governance at nine institutions had left them dangerously undercapitalised.

It injected 400 billion naira into Afribank, Finbank, Intercontinental Bank, Oceanic Bank and Union Bank on August 14 and sacked their top management after the first round of the audit.

Two months later it said it was providing 200 billion naira to four more banks -- Bank PHB, Equitorial Trust Bank, Spring Bank and Wema Bank -- also judged to be facing a grave liquidity crisis.