Today's ETC was the first to report the news on Wednesday.
And according to the interview, which Aftonbladet published, Tobias Billström promises both constitutional amendments and new legislation.
It all started with the state-linked news agency AA in Turkey publishing an article on December 23, after Tobias Billström's visit to Ankara.
AA then reported that Tobias Billström said during his visit that it would be prohibited to wave flags for organizations branded as terrorists, such as the PKK.
Was denied
Tobias Billström's press department subsequently denied that they intended to ban flag waving, according to Aftonbladet, but the interview with Turkish media that Aftonbladet has now published shows the opposite.
Among other things, he reports on new legislative proposals in Sweden that he says the government wants to implement.
- We will also put a proposal in the Riksdag on March 7, which involves a new type of criminal classification in Sweden.
It will make it illegal to promote or propagate terrorist activities in our country.
It can also include waving the flags of terrorist organizations, says Tobias Billström in the interview.
Negotiated the NATO application
During the visit to Ankara in December, Tobias Billström met the Turkish Foreign Minister Mevlüt Cavusoglu.
It was part of the negotiations surrounding Sweden's process to join NATO, which was slowed by Turkey.
Turkey believes that Sweden has not done enough to fight terrorism.
Dagens ETC has spoken to Marie Demker, professor of political science at the University of Gothenburg.
She says that a flag-waving ban could mean a constitutional amendment and questions whether Tobias Billström and the government can get a new law in place as quickly as this summer.
- I find it difficult to see this becoming a crime without it encroaching on people's freedoms and rights, she tells the newspaper.
SVT is looking for Tobias Billström for a comment.