The Australian Greens have condemned the Gillard government's Memorandum of Understanding signed with its Papua New Guinea counterpart to reopen the Manus Island detention centre first used by the former Howard government.

"Ten years after the former Howard government opened it, the Gillard government has shown it has learned nothing from the damage Manus Island caused asylum seekers, let alone how it tainted Australia's international reputation," Greens' immigration spokesperson, Sen. Sarah Hanson-Young, said today.

"This is merely the Pacific Solution reloaded.

"The Greens intend referring the Manus Island proposal to a Senate inquiry, as we've done for the Malaysian deal, because in both cases Parliament has not been allowed to scrutinise the government's intentions. 

"We want to know how much the Manus Island deal will cost Australian taxpayers, who will be expelled there and what happens should their claims for protection be approved.

"The Immigration Minister has also yet to answer how he will uphold his obligations to act in the best interests of the unaccompanied children for whom he is responsible as their legal guardian."