A humanitarian crisis is a great excuse for a few rounds of political point-scoring. And last week's massive earthquake in Peru has proved to be no exception.

It isn't so unusual for donors to stamp their mark on food aid, but thousands of cans of tuna reportedly distributed in the Peruvian quake zone south of Lima appear to have taken the practice to a new level.

Peru's Expreso newspaper carries a photo of a tin with a label sporting photos of Venezuelan President Hugo Chavez and Peruvian opposition politician Ollanta Humala, who lost to Alan Garcia in last year's presidential election.

According to a report in the Los Angeles Times, a message on the label reads: "The Peruvian government acts in an inefficient, slow and heartless manner, notwithstanding the pain of the victims, leaving them to the mercy of hunger, thirst and delinquency."

Not surprisingly, the offending cans have stirred up a political storm.

Humala's Nationalist Party - whose logo also features on the label - has denied responsibility, blaming a "weak and cowardly" campaign to damage its image, according to the Miami Herald. President Garcia said he didn't believe Humala was behind the fishy propaganda. But the Expreso newspaper said the cans were handed out from Nationalist Party trucks, fuelling the theory they could be the brainchild of local Humala or Chavez supporters.

The Venezuelan ambassador to Peru was quick to disassociate his government from the controversial labels. "This is a damaging manipulation, a vile manipulation because Venezuela has brought humanitarian aid, not party politics," he reportedly told Lima's CPN Radio.

The LA Times said the row was symptomatic of a wider divide between South Americans who support the policies of powerful socialist leader Chavez and those who disapprove of his anti-U.S. rhetoric.

President Garcia is a Washington ally who has accused his Venezuelan counterpart of interfering in Peru's affairs. During last year's presidential campaign, he also branded Humala "a Chavez lackey", according to the newspaper. But while there's no love lost between Garcia and Chavez, the Peruvian president has publicly thanked Venezuela for the quake aid it's sent.

As long as the perpetrators of "tuna-gate" remain shrouded in mystery, it's hard to know whether the cans were a roaring a success or a political own-goal.

Either way, the controversy makes Bolivian President Evo Morales look like a saint in comparison. He and his cabinet have promised to donate between 25 percent and half of their pay this month to the tens of thousands of families left homeless by the devastating Peru quake.

"International aid is not always enough when there is a natural disaster, but a small contribution will always help the families affected by the earthquake," Morales said.

Big natural disasters can make or break governments. They can make a town mayor a hero who'll go on to be president, or they can expose the faultlines of state corruption and fuel a revolution.

Sometimes tragedies persuade long-standing enemies to unite and help each other out. Other times governments score goals by giving aid to traditional enemies to highlight their weakness.

In the case of Peru, some quake survivors have got so fed up waiting for help to arrive that they've packed up and left town. According to a report in the Christian Science Monitor, aid workers say there's actually plenty of relief to go round, but the problem lies with distribution bottlenecks.

Some have criticised a decision to put ministers in charge of the relief effort. "Local authorities, the ones who know the area best, and titular head of the civil defense system, have no role. They have been replaced by ministers," Frank Boeren of Oxfam International told the paper.

To those still waiting for relief to trickle through, the tuna scandal must seem like a cruel and cynical sideshow.

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