Authorities in Bulgaria denied involvement in the supply chain of thousands of pagers that detonated on Tuesday in Lebanon in a deadly blow to Hezbollah, Reuters reports.

How or when the pagers were weaponised and remotely detonated remains a public mystery and the hunt for answers has involved Taiwan, Bulgaria, Norway and Romania.

Bulgaria’s state security agency DANS said it had “indisputably established” that no pagers used in the Lebanon attack were imported to, exported from, or made in Bulgaria.

It also said that neither Norta nor its Norwegian owner had traded, sold or bought the pagers within Bulgaria’s jurisdiction.