The pagers used by Hezbollah members that simultaneously exploded on Tuesday came from Taiwan, the New York Times reported, with explosives packed in sometime before they arrived in Lebanon.
At least nine people were killed and some 2,800 wounded, including the Iranian ambassador to Lebanon, when the pagers exploded across the country in an unprecedented attack blamed on Israel.
The pagers had been ordered from Taiwanese manufacturer Gold Apollo, the Times reported, citing anonymous American "and other" officials.
They were tampered with by Israel before arriving into Lebanon, some of the officials told the US newspaper.
A source close to Hezbollah, asking not to be identified, had previously told AFP that "the pagers that exploded concern a shipment recently imported by Hezbollah of 1,000 devices," which appear to have been "sabotaged at source."
The Times reported some 3,000 pagers were ordered from Gold Apollo, mostly its AR924 model.
The blasts "killed nine people, including a girl," Lebanese Health Minister Firass Abiad said.
"For Israel to embed an explosive trigger within the new batch of pagers, they would have likely needed access to the supply chain of these devices," Brussels-based military and security analyst Elijah Magnier told AFP.
"Israeli intelligence has infiltrated the production process, adding an explosive component and remote triggering mechanism into the pagers without raising suspicion," he said, raising the prospect the third party which sold the devices could have been an "intelligence front" set up by Israel for the purpose.
There has been no immediate comment by Israel on the incident.