According to Swedish court documents seen by Aftonbladet, German police suspect at least ten people, residing in Norway, Germany, UK, Switzerland and Iraq, of involvement in the network, known as 'Rawt' or 'the movement'.
The German investigation believes that Krekar, whose real name is Najmuddin Faraj Ahmad, has since 2008 been seeking to build a network of up to 100 European activists, with the goal of fighting to establish an Islamic caliphate in Kurdistan.
"Eligible targets for terrorist acts in Iraq could include coalition troops, political parties, and American and Norwegian civilians," the German police wrote in a request to a Swedish court. "Even suicide bombings, assassinations, snipers and chemical weapons would be allowed."
They believe a 34-year-old Iraqi living in Switzerland, and a 31-year-old Iraqi living in the UK both played a leading role.
The new investigation came to light when German police asked the court to interrogate a 28-year-old Iranian expelled from Norway in 2011, who now lives in Västerås.
The 28-year-old this week told Swedish newspaper Aftonbladet that the interview could put his life at risk.
"I could be executed," he told the paper. "This is incredibly important for my private life. This may have consequences for me in Iran. I could be executed if something leaks out."
According to Norway's VG, Rawt also planned to give financial support to al-Qaeda in the Kurdish republic.
The Germans do not suspect the 28-year-old of any crime, but believe he was involved in chatting to the network in December 2010 and had direct contact with Krekar at least twice over the internet.