The hundreds of pagers that exploded on Tuesday in Lebanon and Syria had apparently been acquired by the militant group Hezbollah after the group’s leader ordered members in February to stop using mobile phones, warning they could be tracked by Israeli intelligence.

The pagers exploded simultaneously, killing at least nine people, including members of Hezbollah, and wounding more than 2,000, including the Iranian ambassador, officials said.

A Hezbollah official told the Associated Press the pagers were a new brand, but declined to say how long they had been in use.

Taiwanese company Gold Apollo said it authorised its brand on the pagers that exploded in Lebanon and Syria, but they were manufactured by a company based in Budapest.

The AR-924 pagers were manufactured by BAC Consulting KFT, based in Hungary’s capital, according to a statement by Gold Apollo.

It said: “According to the co-operation agreement, we authorise BAC to use our brand trademark for product sales in designated regions, but the design and manufacturing of the products are solely the responsibility of BAC.”

Gold Apollo chairman Hsu Ching-kuang told journalists on Wednesday that his company has had a licensing agreement with BAC for the past three years, but did not provide evidence of the contract.

The AR-924 pager, advertised as being “rugged”, contains a rechargeable lithium battery, according to specifications once advertised on Gold Apollo’s website before it was apparently taken down on Tuesday. It could receive text messages of up to 100 characters.

Experts said the pager explosions point to a sophisticated, long-planned operation, possibly carried out by infiltrating the supply chain and rigging the pagers with explosives before they were imported to Lebanon.

Officials pointed the finger at Israel in what appeared to be a sophisticated, remote attack that wounded more than 2,700 people at a time of rising tensions across the Lebanon border.

The Israeli military declined to comment.

A Hezbollah official who spoke on condition of anonymity told The Associated Press that the new brand of handheld pagers used by the group first heated up, then exploded, killing at least two of its members and wounding others.

Lebanon’s health minister, Firas Abiad, said at least eight people were killed and 2,750 wounded — 200 of them critically.

The son of a member of Hezbollah’s bloc in Lebanon’s parliament was among those killed. The sons of two other senior officials were wounded, a Hezbollah official said.

Prominent Hezbollah politician Ali Ammar spoke to the AP after his son, Mahdi, was killed.

“This is a new Israeli aggression against Lebanon,” Mr Ammar said. “The resistance will retaliate in a suitable way at the suitable time.”

A Hezbollah official said the wounded include the son of Hezbollah’s Hassan Fadlallah and the son of senior security official Wafiq Safa. The official spoke on condition of anonymity.

Iranian state-run IRNA news agency said that the country’s ambassador, Mojtaba Amani, was superficially wounded by an exploding pager and was being treated at a hospital.

Photos and videos from Beirut’s southern suburbs circulating on social media and in local media showed people lying on the pavement with wounds on their hands or near their pants pockets.

Hezbollah leader Hassan Nasrallah previously warned the group’s members not to carry mobile phones, saying that they could be used by Israel to track their movements and to carry out targeted strikes.

Lebanon’s Health Ministry called on all hospitals to be on alert to take in emergency patients and for people who own pagers to get away from them. It also asked health workers to avoid using wireless devices.

AP photographers at area hospitals said the emergency rooms were overloaded with patients, many of them with injuries to their limbs, some in serious condition.

The state-run National News Agency said hospitals in southern Lebanon, the eastern Bekaa Valley and Beirut’s southern suburbs — all areas where Hezbollah has a strong presence — had called on people to donate blood of all types.

The news agency reported that in Beirut’s southern suburbs and other areas “the handheld pagers system was detonated using advanced technology, and dozens of injuries were reported”.

The Hezbollah official who spoke on condition of anonymity because he was not authorised to speak to the media said the explosions were the result of “a security operation that targeted the devices”.

“The enemy (Israel) stands behind this security incident,” the official said, without elaborating. He added that the new pagers that Hezbollah members were carrying had lithium batteries that apparently exploded.

Lithium batteries, when overheated, can smoke, melt and even catch on fire. Rechargeable lithium batteries are used in consumer products ranging from phones and laptops to electric cars. Lithium battery fires can burn up to 590C.

The incident comes at a time of heightened tensions between Lebanon and Israel. The Lebanese militant group Hezbollah and Israeli forces have been clashing near-daily for more than 11 months against the backdrop of war between Israel and Hezbollah ally Hamas in Gaza.

The clashes have killed hundreds in Lebanon and dozens in Israel and displaced tens of thousands on both sides of the border. On Tuesday, Israel said that halting Hezbollah’s attacks in the north to allow residents to return to their homes is now an official war goal.

Israel has killed Hamas militants in the past with booby trapped cellphones and it’s widely believed to have been behind the Stuxnet computer virus attack on Iran’s nuclear programme in 2010.

The US says it is gathering information on the pager explosions.

“I can tell you that the US was not involved in it,” US State Department spokesman Matthew Miller said. “The US was not aware of this incident in advance. And at this point, we’re gathering information.”