At least a dozen Jewish families in north-eastern Australia have been evacuated from their homes as a "flood of biblical proportions" ripped through Queensland this week, killing at least 12 people.

More than 50 people are still missing and one Jewish man remains unaccounted for near the rural town of Toowoomba, which was flattened on Monday by what police described as an "inland instant tsunami".

The bulk of Queensland's 6000 Jews live in the state's capital, Brisbane, which was bracing for its river to peak early on Thursday morning as analysts revised up their predictions of the damage bill to $AU13 million, or one per cent of GDP.

Most of Queensland has been declared a disaster zone, with Premier Anna Bligh describing it as the "worst natural disaster in our history".

Jason Steinberg, the president of the Queensland Jewish Board of Deputies, said: "There have been Jewish people evacuated from several towns. We are trying to assess their needs. Homes are being evacuated as a precautionary measure.

"It's an amazing sight," said Mr Steinberg. "Where you once had a clear road, it's a lake. The major arterial roads around Brisbane are now cut off. The main shul is okay. The second shul is fine and the temple is fine."

Levi Jaffe, the rabbi of the Brisbane Hebrew Congregation, took four Torah scrolls to his house on Wednesday. "It's just a precaution, it's on higher ground," said the Manchester-born Chabad rabbi. "In the 1974 floods, the water didn't reach the shul. We're hopeful it won't."

Services have been cancelled this week but Rabbi Jaffe said he would be holding prayers for the 200 member families at his house. "We are bracing. I've never seen anything like this. I stocked up to an extent, but at the supermarket the shelves are completely empty of basic staples. People are quite concerned, there's a bit of a siege mentality."

He said he and his sons helped evacuate a Jewish couple from their inner-city apartment on Wednesday afternoon amid fears the electricity would be cut, leaving the wheelchair-bound woman unable to escape.

"The chances of water reaching them was very high and their family in Melbourne was really worried so we helped them evacuate," he said.

Ari Heber, of Queensland Jewish Community Services, added: "So far we have identified a dozen people in Brisbane whose houses we believe will go under. We are not aware of anyone officially missing, we just don't know where people are at the moment and communications are difficult.

"Everyone is frightened. It's quite scary, the water is quite high and the speed is phenomenal. Tomorrow [Thursday] is going to be the worst, everyone has time to plan. It's very surreal waiting for the water to arrive."