The widescale raid carried out at hosting companies in Stockholm, Västmanland and Västra Götaland targeted one of the world's largest sites for sharing music, games and computer programmes.
According to Swedish Television's news programme, Rapport, the action was the result of contact between the Motion Picture Association of America (MPAA) and the White House.
The US State Department then turned to Stockholm, with a demand for Sweden to do something about The Pirate Bay.
In April a Swedish delegation consisting of representatives of the National Police Department, the Police Board and the Ministry of Justice travelled to Washington to discuss The Pirate Bay.
Swedish police and prosecutors were then given the go-ahead to act. According to one prosecutor the legal situation was still unclear, but the state secretary Dan Eliasson gave the order for the operation to begin, according to Rapport.
"I can guarantee that nobody from the Ministry of Justice gets involved in operational work in individual cases. Neither politicians nor civil servants," Eliasson told TT.
He said that the Swedish delegation and the US authorities simply discussed copyright issues and how to deal with file sharing in general terms, and did not focus on The Pirate Bay specifically.
"We have not had any demands [about The Pirate Bay] from the American authorities at a government level. On the other hand, there are often discussions at a civil servant level about the problem of file sharing and copyright breaches," said Eliasson.
"This happened here too, and of course the big file sharing sites were mentioned."
Eliasson also confirmed that the MPAA has lobbied the Swedish government many times.
"But that's not an American authority, it's an interest group. I have met representatives from the MPAA and they were concerned about the file sharing being run from Sweden. I can't remember whether or not The Pirate Bay was mentioned," he said.
The Centre Party's justice spokesman, Johan Linander, has now asked the parliamentary Constitutional Committee to investigate justice minister Thomas Bodström and others in office.
Linander says that American pressure led Swedish politicians to get involved in the police's operations.
On Thursday Bodström said that he found it hard to believe that anyone would try to direct the Swedish police or prosecutors to make arrests.
"But we have discussed how we should continue the work around the copyright issue," he said, referring to a letter urging the police to increase efforts against illegal file sharing.
Bodström was on a flight on Thursday night and was not contactable.
On Wednesday police arrested three men in their 20s following a report from the film and music organisation Antipiratbyrån. They are suspected of breaking copyright laws.