A first suicide bomber blew up a vehicle packed with explosives to breach a barrier in a southern neighbourhood of Dhuluiyah, which the second bomber then penetrated, the sources said.
Security forces and allied tribesmen then clashed with the militants in the Jubur neighbourhood.
Dhuluiyah was previously overrun by militants but local tribes drove them out, and Jubur has put up fierce resistance to renewed attempts by the militants to take the town.
More than 50 people were wounded today's violence, the sources said.