The Iranian-backed Lebanese group Hezbollah said on Friday it could kill tens of thousands of Israelis by striking specific targets in Israel with what it described as precision-guided rockets.

"I tell the Israelis that you have a number of targets, not a large number ... that can be hit with precision rockets ... which we have," Hezbollah Secretary General Hassan Nasrallah said in a broadcast speech.

He said he would not name the targets and did not say whether the rockets were newly acquired weapons.

The threat came as Israel continued to debate whether to attack Iranian nuclear facilities. Such a move could trigger retaliation from Iran's allies, like Hezbollah. Nasrallah said Iran's response to any Israeli attack would be "lightning" and huge.

Nasrallah said his group could strike a limited number of targets in Israel which if hit would lead to mass casualties - a possible reference to Israeli nuclear facilities, though he said he did not spell out what he meant.

Israel, the only Middle East country outside the nuclear Non-Proliferation Treaty (NPT), has never confirmed or denied having nuclear weapons.

"Hitting these targets with a small number of rockets will turn ... the lives of hundreds of thousands of Zionists to real hell, and we can talk about tens of thousands of dead," said Nasrallah.

Nasrallah was speaking on the occasion of al-Quds Day, marked each year on the last Friday of Ramadan in accordance with a tradition established by Ayatollah Ruhollah Khomeini, the late supreme leader of Iran.

In Iran on Friday, hundreds of thousands of people turned out across the country to march in Jerusalem Day events organized by the state. Speaking at Tehran University, Iranian President Mahmoud Ahmadinejad called Israel's existence an "insult to all humanity."

In Bahrain, police forces clashed with protesters who attempted tohold their annual rallies marking the day. Several people wereinjured and others arrested during the clashes that began earlyFriday morning.

Meanwhile, in Tunisia some 200 Salafi Islamists attacked a Jerusalem Day festival at a youth center in the north of the country, injuring five people.

The organizers of the event told local media the demonstrators were angered by the presence of Samir Qantar, a Lebanese former member of the Palestinian Liberation Front and a supporter of Hezbollah. The organizers said Qantar, who spent 29 years in prison in Israel, angered local Salafis by expressing support at the meeting for Syrian President Bashar Assad.

The attack was the latest in a string of attacks by extremist Salafis on cultural events in the country.