Earlier this week an asylum seeker was arrested on suspicion of murdering a female employee at a refugee centre
Up to 80,000 migrants who arrived in Sweden last year are going to be expelled from the country, its interior minister has announced.
Anders Ygeman said thousands of migrants' asylum applications had been rejected.
"We are talking about 60,000 people but the number could climb to 80,000," he was quoted as saying by Swedish media.
He said the expulsions would be staggered over several years.
Police and authorities in charge of migrants have been asked to organise the expulsion.
Migrants whose applications are rejected are normally taken out of Sweden using commercial flights.
But because of the large number being rejected they would use specially chartered aircraft to take them out of the country, Mr Ygeman said.
Sweden accepted more than 160,000 asylum seekers last year, putting it among the EU states with the highest proportion of refugees per capita.
The number of migrant arrivals has dropped sharply since it brought in systematic photo ID checks for travellers earlier this month.
The announcement comes after a teenage asylum seeker was arrested on suspicion of murdering a female employee at a youth refugee centre in Molndal, near Gothenburg, earlier this week.
A motive for the stabbing attack was not clear, but her death has led to questions about overcrowded conditions in some centres, with too few adults and employees to look after children, many traumatised by war.
Meanwhile, neighbouring Denmark voted in favour of seizing the assets of asylum seekers to help pay for their stay while their claims are processed.
Valuables worth more than about €1,300 will be seized by police as migrants enter the country to help cover their housing and food costs.
Some have likened the new measures to the Nazis confiscating gold and other valuables from Jews during the Holocaust.
President of the Danish National Party, Kashif Ahmad, said: "There is a connotation and similarity to the 1930s and 1940s in Germany where we saw the Nazis confiscating large amounts of gold from Jews and others".
"Therefore I believe it's a disgrace and it's a shameful law that we passed".
It is part of a package of immigration reforms designed to make Denmark less appealing for migrants.