BEIRUT, Aug 17 (Reuters) - 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.

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 Jerusalem 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. (Reporting by Tom Perry; Editing by Jon Hemming)