Security sources told Reuters that the devices had been procured in recent months.
The charge could be set to trigger on receipt of a particular message or even simply timed to explode with an old-fashioned timer, said Mr Woodward.
Ken Munro, the founder of the cyber security company Pen Test Partners, said: “I’m leaning hard towards a supply chain attack, as to remotely cause a battery to explode in such a fashion would be extremely challenging.”
Intriguingly, the attack came hours after Israel’s domestic security agency said that it had foiled a similar – though much smaller-scale – plot by Hezbollah.
Shin Bet said in a statement it had seized an explosive device attached to a remote detonation system, using a mobile phone and a camera that Hezbollah had planned to use to kill a former Israeli military official in Tel Aviv.
It said the group had planned to operate the device remotely from Lebanon.
The attack comes a day after Israel’s defence minister said that the country would take military action to return civilians to the north of the country, stoking fears of an all-out Israel-Hezbollah war.
It follows nearly a year of low-level but intensifying conflict, and came a day after the Israeli government made returning evacuated 60,000 civilians to their homes in the north of the country an official war goal.
The fighting began when Hezbollah launched strikes following Israel’s attack on Hamas in Gaza in response to the Oct 7 terrorist attacks.
The conflict has mostly been concentrated along the Lebanon-Israel border, but it has also seen Israeli air strikes across Lebanon and Hezbollah rocket strikes deep into Israel.
Although so far both sides have shied away from attacks on a scale likely to spark a full-scale war, thousands of civilians have fled from both sides of the frontier.
Yoav Gallant, the Israeli defence minister, told Amos Hochstein, a visiting US envoy, this week that the window for a negotiated end to the fighting with Hezbollah was closing.
It meant that “the only way left to ensure the return of Israel’s northern communities to their homes will be via military action”.