Mahmoud al-Mabhouh was murdered in his hotel room in Dubai on Jan 20.
According to reports, Hamas had accused Israel behind the killing and vowed revenge.
Police chief Lt Gen Dhafi Khalfan Tamim said, a Eurpoean hit squad assassinated Mabhouh using faked British and Irish passports.
He said that six of the suspects had British passports, three were Irish, one French and one German.
The Britons were named as James Leonard Clarke, Stephen Daniel Hodes, Paul John Keeley, Michael Lawrence Barney, Jonathan Lewis Graham and Melvyn Adam Mildiner.
One of the group was a woman with Irish papers in the name of Gail Folliard. The other Irish suspects were named as Kevin Daveron and Evan Dennings.
A CCTV footage showed the group entering the hotel where Mabhouh was staying, Tamim said.
Tamim admitted it was possible that "leaders of certain countries gave orders to their intelligence agents to kill" the Hamas man.