One person was killed and dozens wounded, two of them seriously, as several rockets landed up to 70 kilometres inside Israel, the deepest so far.
At least 40 of the mostly inaccurate rockets struck populated areas causing severe damage to several buildings.
A 60 year old man was killed when a rocket slammed into a kibbutz near Nahariya, six kilometres south of the border, as he was riding his bicycle on his way to the bomb shelter.
One of the rockets hit near the city of Beit Shean, about 60 kilometres from the Lebanese border, the deepest strike into Israel since the start of the Lebanon conflict.
The Beit Shean strike marked the first time that a Hezbollah rocket had hit close to Israel's central region, the nation's most populated area.
Rockets also struck across the north of the country, including in the towns of Kiryat Shmona, Nahariya, Safed, Maalot, Carmiel and Acre.
A Syrian-made Fajer-5 missile, with a longer range and larger warhead, was fired from Lebanon for the first time, hitting the northern town of Rosh Pina and causing no injuries.
Hezbollah also claimed it had hit the town of Afula, 50 kilometres from the closest border point, with a salvo of what it calls Khaibar-1 rockets. It first claimed to have struck Afula with Khaibars on Friday.
The militia has fired more than 2,000 rockets at northern Israel since the start of the Lebanon offensive on July 12, killing 19 civilians.
Nineteen civilians have been killed as a result of rocket fire in Israel since the start of the Lebanon offensive 22 days ago. Thirty-six Israeli soldiers have also been killed in the fighting.
Qana a mistake
Meanwhile the Israeli military's inquiry into its devastating bombing in the southern Lebanese town of Qana has found it made a mistake and did not know civilians were in the building it attacked.
But it accuses Hezbollah guerrillas used civilians as shields for their rocket attacks, according to a statement.
The Lebanese hospital officials have revised down to 28 the number of people killed in the Qana bombing - the figure had initially been put at 52 dead.
The revised toll follows an earlier statement by the US-based rights watchdog Human Rights Watch which put the death toll at 28, with 13 missing.
"Twenty-eight people are confirmed dead, including 16 children, and nine were wounded," said officials at the Tyre government hospital where all the victims of Sunday's attack were taken.
The initial estimate was based on a register of over 50 people who had sought shelter in the basement of the building that was struck.
In a statement summarising the inquiry report, the Israeli military said Israel did not know there were civilians in the building.
"Had the information indicated that civilians were present the attack would not have been carried out," the statement said.
The bombing followed guidelines regarding attacking "suspicious structures" in villages where civilians have been warned to evacuate, the statement said.
It said that Hezbollah forces "use civilian structures inside villages to store weaponry and hide in after launching rocket attacks".
The statement said more than 150 rockets have been launched from Qana and the area around it since July 12, when the current conflict erupted.
As a result of the incident, the statement said, the guidelines would be evaluated and updated.
The chief of staff of the Israeli military Dan Halutz apologised for the loss of civilian life but claimed that Hezbollah "uses civilians as human shields and intentionally operates from within civilian villages and infrastructure".