South Australia has toughened its COVID-19 testing regime for people arriving from New South Wales, Victoria and the ACT in what Premier Steven Marshall described as two extra “speed bumps” in the short-term to try to prevent the omicron variant coming into the state.

Mr Marshall said on Saturday morning that health authorities in the state are highly concerned about the omicron variant of COVID-19, as he left open the prospect of closing the interstate borders again with NSW, Victoria and ACT in coming days.