The suicide bomber caused the twin blasts in a busy area of downtown Stockholm Saturday evening, in an attack probably meant to wreak carnage among Christmas shoppers.
“The FBI is sending a group of seven experts to Sweden,” Säpo spokeswoman Sara Kvarnström told AFP.
“From what I understand, they offered their help after Saturday’s events and we said yes.”
Speaking with the TT news agency, Swedish justice minister Beatrice Ask welcomed the FBI’s offer.
“This is a good example of how international police cooperation works,” she said.
“It’s especially important for a small country like Sweden that doesn’t have all the expertise.”
The FBI group heading to Sweden includes specialists in tracing explosives and who have knowledge of the methods terrorists have used in other bombings around the world.
“It’s incredibly valuable knowledge,” said Ask.
Islamic website Shumukh al-Islam named Taimour Abdulwahab as the attacker, saying he had “carried out the martyrdom operation in Stockholm.”
A Swedish prosecutor said investigators were almost sure it was the same man.
In messages before the blasts, the bomber said he targeted Sweden over its military presence in Afghanistan and support of artist Lars Vilks, who drew the Prophet Mohammed with the body of a dog in 2007.
British and Norwegian authorities had also offered to help in the investigation, Ask told TT.