Warm-hearted Australians would be "devastatingly disappointed" with Labor's solution to boat people, Greens immigration spokeswoman Senator Sarah Hanson-Young says.
"Warm-hearted Australians and Labor voters will be devastatingly disappointed because this deal is about cruelty to refugees, not about caring for them," she said in Melbourne on Saturday.
"It is a rush to cruelty as Kevin Rudd rushes to the polls."
She called for the government to release the full costings of the deal with Papua New Guinea and any legal advice it has received in relation to the arrangement.
"We are only possibly weeks away from polling day ... and it's important that the government is absolutely transparent with the Australian people about how much this deal is costing," she said.
Despite the Greens' senator describing the ALP's new approach to asylum seekers as more cruel and harsh than previous prime minister John Howard's policy, she would not rule out the Greens making a deal with Labor for leadership in the future.
"It is a total hypothetical question, what I can say is the Greens will never support this policy," she said.