BANGKOK/KUALA LUMPUR — Thai authorities investigating bomb attacks across the country last week have traced a phone found in the Phuket bombing to Malaysia, reported Al Jazeera.

The bombings several people and injured dozens — including foreigners — at popular tourist spots across southern Thailand last Thursday and Friday.

Inside the partially destroyed device, investigators discovered a serial number belonging to the Malaysian Communications And Multimedia Commission, Malaysia’s communications regulator. Malay and Thai authorities are working to identify the owner of the device, reported Malaysian news site The Star Online.

Meanwhile, Thai authorities discovered more unexploded bombs in Hua Hin and Phuket over the weekend, the Bangkok Post reported. The cell phone bombs are reportedly similar to those used in Friday’s attacks, requiring a phone call for detonation.