The Papua New Guinea opposition has called for the resignation of Prime Minister Sir Michael Somare after attempts to halt investigations against him.

The National newspaper reports the country's anti-corruption watchdog, the Ombudsman Commission, is investigating allegations that Sir Michael failed to lodge annual returns, lodged returns late, or lodged incomplete returns between 1994 and 2003.

Failing to file annual returns is an offence and Sir Michael could face prosecution.

Chief Ombudsman Ila Geno was about to convey the commission's decision on the allegations personally to Sir Michael, when lawyers representing the prime minister launched court actions.

In the court papers filed, Sir Michael claimed that the commission's actions were unfair.

He is seeking a permanent bar on the investigations.

The Opposition has called on the Prime Minister to immediately step aside so that the investigations can proceed unhindered.

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