Wallabies are getting "as high as a kite" on opium in Australian poppy fields and flattening crops as they hop round in circles, according to a report.

The marsupials, which look like small kangaroos, have been getting into medical opium crops in the southern island state of Tasmania and chewing on the plant's intoxicating heads, state officials said.

"We have a problem with wallabies entering poppy fields, getting as high as a kite and going around in circles," state attorney-general Lara Giddings told a parliamentary estimates hearing.

"Then they crash. We see crop circles in the poppy industry from wallabies that are high," local media reported Ms Giddings as saying.

Tasmania is the world's largest producer of legally-grown opium for the pharmaceutical market, with about 500 farms supplying approximately 50 percent of the raw material for morphine and other opiate drugs.

Livestock and other animals, such as deer and sheep, which eat the plants had also been seen acting "weird," industry spokesman Rick Rockliff said.

"There have been many stories about sheep that have eaten some of the poppies after harvesting and they all walk around in circles," he said.