Priti Patel’s plans to process asylum seekers abroad are facing a Conservative rebellion next week, with MPs calling the proposal “clearly ridiculous” ahead of a vote on the nationality and borders bill. Amendments circulated among senior Tories include attempts to scupper government plans to set up offshoring centres and a proposal to instead create a global resettlement scheme to accept 10,000 people a year from war-torn regions. Rebels believe they could gather the support of dozens of MPs on Tuesday, when the controversial bill returns to the Commons, after a softening in attitudes in the wake of the Ukrainian refugee crisis. They remain unsure whether they have enough support to overturn the government’s 77-seat working majority, however. In an email circulated among potential rebels, the former chief whip Andrew Mitchell described the government’s offshoring plans as “a moral, financial and practical failure”, adding that the suggestion the government could use Ascension Island, a remote UK territory in the Atlantic Ocean, as a processing centre was “absurd” and risks exposing women and children to abuse. “We would have to build a British Guantánamo Bay and [use] RAF planes,” he wrote. He also claimed that the cost to taxpayers would be £2m per person, adding: “If we were to place asylum seekers at the Ritz [hotel] it would only cost £250k a year.” Ministers see Australian-style offshore processing centres – to which migrants would be flown within seven days of arriving in the UK – as a key potential deterrent to stem the record surge in Channel crossings. At the same time, the government appears to be observing a softening in public attitudes towards asylum seekers amid the war in Ukraine. David Davis, the former Brexit secretary, said: “I find it hard to image that in the current climate they are going to send Ukrainian asylum seekers offshore if they arrive here by boat. If you can’t do it to a Ukrainian asylum seeker, how are you going to do it to anyone else?” The former Home Office minister Damian Green also plans to rebel and support an amendment passed in the Lords that sets up a permanent, legal route for asylum seekers. Conservatives are being urged to support an amendment to create a “safe statutory resettlement scheme which can be ‘flexed in response to crises’”. Referring to Ukraine, the email reads: “Never again should the government experience the chaos of the last few weeks or the months of chaos following the fall of Kabul.” The bill returns to the Commons after the Lords voted to remove clause 28, which would allow asylum seekers to be removed from the UK and sent overseas to a third country for their asylum claim to be processed. Michelle Bachelet, the UN high commissioner for human rights, said on Thursday that the proposal to move refugees abroad while their claims are processed would violate their rights. “The proposed offshore processing centres would expose asylum seekers to real risks of forced transfers, extended periods of isolation and deprivation of liberty, violating their human rights and dignity,” said Bachelet, who was jailed and tortured under the Pinochet regime in Chile. Patel has signalled that she wishes to go ahead with offshore plans. Last month, she recruited the former Australian foreign minister Alexander Downer to review the country’s border force, weeks after he had urged the UK to adopt a hardline on boat migrants. But so far, the search to find a willing venue to base an offshore centre has been knocked back. Officials from Albania and Ghana have denied claims from Home Office officials that they are in talks to set up a processing centre. So far this year, the UK authorities have rescued or intercepted 2,923 people making the dangerous journey in 97 boats. Last year that figure was not reached until 13 May. A Home Office spokesperson said: “Our nationality and borders bill … will fix our broken asylum system so we prevent people from making dangerous journeys to the UK and protect the those in need through safe and legal routes. “The Lords’ votes … are disappointing, but we will not be deterred from delivering what the people of this country voted for.”