Knitting nannas against kids in detention

A bunch of Tassie nannas armed with knitting needles have launched a campaign to free children from detention and they've attracted some political backing.

Each Friday for almost six months the Tassie Nannas have set up in Hobart's city mall, quietly going about their work, but the message is loud, spokeswoman Trish Moran said.

"These people ran from appalling situations, seeking safe refuge in Australia," she said.

"Instead they are stuck in a crude camp with inadequate facilities in a former guano pit on the tiny island of Nauru."

On Friday the group will be joined by federal senators - independent Jacqui Lambie, Labor's Carol Brown and Green Nick McKim - to strengthen their war cry.

"It's time to close all the camps and free the children," Ms Moran said.

The upper house trio will do some knitting in the mall from noon (AEST).