"More than half the animals that die on export vessels die because of this syndrome," Hahnheuser told Reuters.

The syndrome is formally known as inanition. Sheep stop eating because of stress.

Australia's A$1 billion (389 million pounds) a year live sheep and cattle export trade grabbed headlines late last year when more than 50,000 Australian sheep were stranded at sea for more than three months after being rejected at a Saudi Arabia.

The saga ended when the sheep were accepted by Eritrea, together with a A$1 million handling fee, as food aid.

Hahnheuser said their hunger strike would highlight the fact that political leaders seemed to think it acceptable that sheep should starve.

"The whole idea of a hunger strike is highly relevant to what (Labour leader) Mark Latham and (Prime Minister) John Howard say is appropriate ways to treat Australian sheep," he said.

Hahnheuser and Lang will start their hunger strike on Monday after Hahnheuser appears in court in Victoria state accused of contaminating a shipment of 70,000 sheep bound for the Middle East by feeding them rendered pig meat, which Muslims do not eat.

Howard has been stalked in recent days by a woman dressed as a sheep, also protesting against the live export trade. The woman has turned up at venues visited by Howard as he campaigns through Western Australia state.

Australia's conservative government, seeking a fourth consecutive term in government, and centre-left opposition Labor are polling neck-and-neck at the half-way mark in the election campaign.