Two migrants were in hospital after authorities pulled them from icy waters off Denmark on Monday as they tried to reach Sweden to ask for asylum, Danish police said.
The rescued migrants were part of a group of four who attempted crossing the strait between Denmark and Sweden, where the water is around eight degrees Celsius (46 degrees Fahrenheit).
"There were two who were taken to hospital after the rescue operation," police spokesman Henrik Svejstrup told local Danish broadcaster TV 2 Lorry.
"One was put on a respirator, but we expect him to be taken out of the coma" later on Tuesday, he added.
Many migrants perceive Sweden as a more attractive destination than Denmark, where measures to reduce immigration have included passing a law that allows police to search asylum seekers for valuables.
Before setting out, the group was reportedly staying at an asylum seeker centre 25 kilometres (16 miles) northwest of Copenhagen. Police did not disclose the migrants' nationalities.
During the crossing the group landed on the sparsely populated island of Saltholm, around four kilometres off the Danish coast.
Two of the migrants knocked on one resident's door, prompting her to call police on Monday.
"They asked if they were in Sweden, and said that they wanted to apply for asylum," the chairman of a local group for residents and farmers, Dirch Jansen Schmidt, told AFP.
"She told them they were still in Denmark. She gave them two glasses of water and then they left," he added.
This was not an isolated case of migrants trying to reach Sweden, which registered 163,000 asylum applications last year and is known for its generous asylum policies.
Danish authorities said earlier this month that between January 4 and April 13, 46 people had tried to walk through a train tunnel leading to the Oresund bridge that connects Denmark with Sweden.
Sweden on January 4 began requiring rail, bus and ferry companies to verify the identities of people travelling from Denmark, significantly reducing the number of migrants who are able to enter the country to claim asylum.
Since a spike in applications last year, Stockholm's centre-left government has said it would introduce temporary residence permits and make it harder to obtain family reunifications.