They are said to have been painted in 1982, but experts have argued that the type of cardboard used was not used until 1994.
Jean-Michel Basquiat, who lived and worked in New York, enjoyed great success during the neo-expressionist movement of the 1980s.
He died of an overdose in 1988, aged 27 years.
According to the house search, people have had their eyes on the paintings since they were discovered in 2012 after being stored in a warehouse for 30 years.
The works are part of the exhibition "Heroes and monsters" and would have been shown until next summer and then shipped to Italy.
The total value of the seized works of art is estimated at SEK 1 billion.