Foreign Minister Julie Bishop says the "chilling" incident which has left a British man and woman critically ill after being exposed to the nerve agent Novichok is deeply concerning.
The pair were hospitalised after being found unwell on Saturday in Amesbury, near Salisbury, where former Russian agent Sergei Skripal and his daughter Yulia were attacked with the same nerve agent in March.
"It is chilling to think that it's the same nerve agent that was responsible for the Salisbury incident in the UK earlier this year," Ms Bishop told reporters in Darwin on Thursday, adding she had spoken to the British high commissioner.
She said Australia was deeply concerned about the fresh illnesses but it was too early to speculate on where it had come from.
Ms Bishop said Russia's actions had long been troubling to western nations, reiterating her view the country should not be readmitted to the G7.
"Russia should not be rewarded for its bad behaviour," she said.
Russia's role in bringing down Malaysian Airlines flight MH17 killing 38 Australians among 298 people aboard, support for the Assad regime in Syria and the Skripal attack are among the recent issues Australia has protested.
"Russia is a great concern to Australia," Ms Bishop said.
A 44-year-old woman and a 45-year-old man were found ill, 11 kilometres north of Salisbury where the Skripals were attacked in March.
Britain has accused Russia of poisoning the Skripals with Novichok, a nerve agent developed by the Soviet military during the Cold War.
Russia denies any involvement.
Australian Associated Press
