Sweden is considering the expulsion of up to 80,000 immigrants who have seen their asylum applications refused, Interior Minister Anders Ygeman says.
"I think it is in any event 60,000 people, but it could be up to 80,000," Ygeman was quoted as saying by the Dagens Industri paper.
"We have a large challenge ahead," he said.
Police and migration authorities had been ordered to prepare the expulsions, the report said.
"We must increase resources and improve the cooperation between authorities," Ygeman said.
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Around 160,000 migrants applied for asylum in Sweden in 2015, the report said, with an estimated 45 per cent refused.
Sweden would try to provide conditions for voluntary return of asylum seekers, but "if we are not successful, then there must be returns assisted by force," Ygeman said.
There was a significant risk that large numbers of those affected will disappear out of sight of the authorities, the report cited a Swedish government source as saying.
Stockholm was already in talks with Afghanistan and Morocco about the return of citizens from those countries, the report said.
Most of the asylum seekers in 2015 were from Syria and Afghanistan, with the next largest group coming from Iraq, according to the Swedish immigration authority Migrationsverket.
The minister later told Swedish television that the focus was on voluntary returns and on motivating people to go back to their countries of origin, "but ultimately we have to be prepared to use force."
Authorities must also be prepared to act against employers who exploit people staying in Sweden without permission and "ensure that it doesn't pay to remain illegally," Ygeman said.
Patrik Engstrom, head of the border police, told Dagens Industri that more police officers will be needed.
The police also need to work much closer with the Migration Agency and be present when an asylum seeker is notified that his or her bid has been rejected as that is when many "disappear," he added.
To carry out the expulsions, Ygeman said, a likely option would be to charter planes, perhaps in co-operation with the European Union.
