NAIROBI, March 21 (Reuters) - Somalia's corruption watchdog will soon publish a report showing financial irregularities in most government ministries, the auditor general said, findings likely to strain relations with donors helping to rebuild the east African country.

Western and other donors have poured billions of dollars into Somalia, funding the army's battle against Islamist insurgents and helping to rebuild vital state institutions destroyed during decades of war between rival clan militias and Islamist warlords.

The donors complain President Hassan Sheikh Mohamud's cash-strapped government is not doing enough to tackle corruption and say the theft of scarce government resources has frustrated efforts to build a functioning state.

Nur Jumale Farah, Somalia's auditor general, said his office had investigated all 25 government ministries and would publish the findings when lawmakers return to the parliament next month following a recess.