Morocco bombing investigation goes international

Casablanca, Morocco (CNN) -- Three more suspects have been arrested in connection with the April 28 bombing in Marrakech which killed 17 people and injured 20 others.

CNN learned Wednesday from security sources that Moroccan police have apprehended three Moroccan males in the coastal town of Safi, the hometown of the alleged chief perpetrator of the bombing, Adil El Atmani. This brings the total number of arrests in Morocco to six.

The sources confirmed that El Atmani is the chief suspect held by the police, following press speculation this week that he was being held, which was unconfirmed by the Moroccan government.

The security sources also confirmed that Moroccan authorities are working closely with the FBI and German police. They pointed to the recent arrests in Germany of three men, two of them with connections to Morocco, who are accused of plotting terror attacks in Germany. They said those arrests came the day after the Marrakech attack, and that the leader of the German cell is a Moroccan who was in contact with El Atmani before the Marrakech bombing and is known by German security services to be both an operative of al Qaeda in the Islamic Maghreb and an expert in explosives.

AQIM has denied any link to the Marrakech bombing, but the denial is being met with increasing skepticism by some Moroccan news media. An editorial in the French-language daily Aujourd'hui said the statement by the North African al Qaeda cell -- put out a week after the bombing -- was unprecedented and "contradicts itself."

On Wednesday, Moroccan authorities held a staged reconstruction of the bombing in Marrakech, which tore through a café. Authorities have said the bomber remotely triggered two explosives, which he had placed there while disguised as a Western hippie.