Original:  However, Time magazine cited a "western intelligence source" as saying that Mossad was behind the blast, and other reports, which were attributed to western intelligence services , also mentioned the involvement of Israel's intelligence services.
Revised:  However, Time magazine cited a "western intelligence source" as saying that Mossad was behind the blast, and other reports, which were also attributed to intelligence services in the West, likewise mentioned the involvement of Israel's intelligence services.
Edit intent: style