JERUSALEM — The Lebanese militant group Hezbollah has significantly expanded its ability to strike deep into Israel with rockets that can now reach the Jewish state's largest cities, and now possesses tens of thousands of projectiles, Israel's army chief said Tuesday.

The remarks by Maj. Gen. Gabi Ashkenazi were the first official assessment of the guerrilla group's capabilities since Israel seized a ship last week carrying weapons allegedly destined for Hezbollah.

Ashkenazi indicated that the arms bust had little effect in stopping what Israel says has been a massive arms buildup by the Iranian-backed militia since the sides fought a bitter monthlong war in 2006.

An official said that Ashkenazi told lawmakers Tuesday that some of the rockets can fly up to 325 kilometers. That would put Jerusalem and Tel Aviv, as well as Israel's nuclear reactor in the southern desert, within rocket range.

Alternatively, the official said, Hezbollah could pound Israeli towns and cities closer to the border from positions north of the Litani River, outside the area of south Lebanon policed by UN peacekeepers.

Ashkenazi was briefing the Israeli parliament's influential Foreign Affairs and Defense Committee. The official spoke on condition of anonymity because the meeting was closed.

A lawmaker present at the briefing said Ashkenazi told legislators Israel would hold the Lebanese government responsible for any attacks by Hezbollah. "Everything that happens in Lebanese territory is the responsibility of the Lebanese government," she quoted him as saying.

There was no immediate reaction from Hezbollah. But its leader, Sheik Hassan Nasrallah, has bragged recently that the group can now strike any Israeli city.

After months of wrangling, Lebanon's prime minister formed a Cabinet Monday that includes Hezbollah ministers. Some observers suggest the arrangement could give Hezbollah virtual veto power over government decisions.

Israel said the huge weapons haul backs up its long-standing contention that Iran is supplying large quantities of arms to Hezbollah and Hamas, the Palestinian militant group that governs the Gaza Strip to Israel's south. Hezbollah denied any connection to the weapons.

During the 2006 war, Hezbollah fired nearly 4,000 Katyusha rockets across Israel's northern border, some of which fell as far as 90 kilometres inside Israel.

Israel went after Hezbollah in a massive air, sea and ground campaign in which nearly 1,200 people died in Lebanon and 159 lost their lives in Israel. The war ended with a UN resolution that bans Hezbollah and other militias and their weapons from the area south of the Litani.

Israel has repeatedly accused Hezbollah of violating that cease-fire and says Iran and Syria are colluding in smuggling arms to the group. Israeli officials have said they believe Hezbollah has managed to triple its prewar arms stockpile to more than 40,000 rockets.

Last week, Israel seized a ship that it says was carrying hundreds of tons of Iranian-made weapons to Hezbollah.

The seizure at sea came a day after Israeli officials said Hamas tested an Iranian rocket that can hit Tel Aviv -- bringing to the fore Israeli fears that both Hezbollah and Hamas are rearming for more confrontations.

Last winter, Israel carried out a devastating military offensive against Hamas. Some 1,400 Palestinians, including hundreds of civilians, were killed. Thirteen Israelis also died in the fighting.

The Israeli assault on Gaza came in response to years of Hamas rocket fire into Israel, which has reached as far as Beersheba, a major Israeli city 37 kilometres from the Gaza border.

At Tuesday's meeting, Ashkenazi said a rocket-defense system that Israel is developing is on course to enter service next year. The laser-based "Iron Dome" system is meant to counter Hezbollah's Katyushas and the more primitive Qassam rockets fired from Gaza.

Despite last week's reported Hamas missile test, the militant group does not appear to be looking for another round of fighting with Israel "at this time," Ashkenazi said.