HARARE (Reuters) - As he celebrated his 93rd birthday on Tuesday, Zimbabwe President Robert Mugabe brushed aside persistent allegations of corruption against senior officials, saying rumor-mongers were merely targeting “big fish” in his administration.

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In comments to be aired on state media on Tuesday, the world’s oldest leader said he would act if shown evidence - even though graft scandals involving ministers and even members of his own family are regular fare in local newspapers.

“I think the big fish, more of it has been talk, talk and talk. People have not come out and actually said here is a case against a big fish,” Mugabe said in the pre-recorded interview.

“Or are people afraid to come out and even come to us and say ‘This one is stealing so much, investigate the person?’ If there is evidence, we will pursue that evidence and certainly we will deal with those persons.”

Despite the almost daily slew of scandals involving state tenders and contracts reported in Zimbabwe’s free-wheeling private media, investigations are rare and arrests even rarer.

The anti-corruption commission is currently fighting the higher education minister and his deputy, who are accused of embezzling hundreds of thousands of dollars from a state fund. They deny the charges.

Parliament has also penned several reports recommending investigations into irregular tender allocations, including at several state-owned firms. The reports have been ignored.

Transparency International said in October Zimbabwe ranked poorly on corruption and was losing at least $1 billion annually to graft, with police and local government officials among the worst offenders.

The opposition says corruption has flourished under the leadership of Mugabe, whom they accuse of running a patronage network that rewards supporters and turns a blind eye to graft.

Mugabe, who has maintained a tight grip on power in the southern African nation since independence from Britain in 1980, is due to stand for re-election next year, saying the ruling party has no viable alternative candidates.

Employees in Mugabe’s office held a small birthday party for him on Tuesday, ahead of a weekly cabinet meeting. A bigger celebration is set for Saturday in Matopos, 500 km (350 miles) southwest of Harare.

The state-owned Herald newspaper carried a 24-page birthday supplement, packed with goodwill messages from government departments.