BEIRUT — The leader of the Lebanese-based terrorist organization Hezbollah on Friday blamed Sunni extremists for a string of attacks targeting the group’s strongholds over the past few months, including a car bombing that killed 22 people and wounded more than 300 on Thursday

Sheik Hassan Nasrallah said all preliminary investigations showed Takfiri groups — a term for Sunni radicals — were likely behind the bombing in a predominantly Shiite southern suburb of Beirut, as well as other recent attacks. He said those groups “serve the interests of Israel.”

The Hezbollah chief acknowledged that Israel’s complicity in the attack had not yet been proven, but said the likelihood of Israeli and American intelligence services’ involvement could be ruled out.

Israeli and American intelligence had doubtless played a role in the bombing in the Hezbollah stronghold, he said, and “no one should say” that he was exculpating Israel. But “the operational” element of the attack was carried out by Sunni extremists, he made plain.

Lebanon’s Prime Minister Michel Suleiman and other Lebanese figures on Thursday blamed Israel for the blast, a notion that was dismissed Friday by Israel’s President Shimon Peres.

He also pledged to double the number of Hezbollah forces in neighboring Syria, fighting to support the regime of President Bashar Assad.

“If you think that by killing our women and children … and destroying our neighborhoods, villages and cities we will retreat or back away from our position, you are wrong,” he said in a speech to supporters marking the end of the 2006 monthlong war with Israel, known in Israel as the Second Lebanon War.

“If the battle with these terrorist Takfiris requires for me personally and all of Hezbollah to go to Syria, we will go to Syria,” he said, drawing thunderous applause from thousands of supporters gathered in a village in south Lebanon bordering Israel. The crowd watched him speak on a large screen via satellite link.

Nasrallah added, “these godless organizations have no religion. They are murderers and they are neither Syrian nor Palestinian or Muslim.”

He also spoke indirectly of an incident last week where four Israeli soldiers were injured, possibly inside Lebanon’s territory: “Not a single Israeli soldier will be able to take one step on Lebanese soil to contaminate it — the same territory purified with the blood of our martyrs.”

“The Israeli’s tourism era in Lebanon is over,” Nasrallah added. “We will cut off the legs and neck of every Israeli entering Lebanon.”

Thursday’s car bomb struck a crowded street in the Rweiss district in Beirut’s southern suburbs, an overwhelmingly Shiite area and stronghold of Hezbollah. The explosion sent a massive plume of black smoke billowing into the sky, set several cars and buildings ablaze and trapped dozens of residents in their homes for hours.

The bombing was the second in just more than a month to hit one of the Shiite group’s bastions of support, and the deadliest since 1985 when a blast in the area killed 80 people. Many in Lebanon see the attacks as retaliation for Hezbollah’s armed support for Assad in Syria’s civil war.

The group’s fighters played a key role in a recent regime victory in the town of Qusair near the Lebanese border, and Syrian activists say Hezbollah guerrillas are now aiding a regime offensive in the besieged city of Homs.

Syrian rebels have threatened to retaliate against Hezbollah for intervening on behalf of Assad. Thursday’s car bombing raises the worrying specter of Lebanon being pulled further into the Syrian civil war, which is being fought on increasingly sectarian lines pitting Sunnis against Shiites.

Nasrallah said his response to such bombings will be to double the number of fighters in Syria, if the need arises.

“Just like we won all our wars with Israel, we will win the war on the terror of the godless organizations,” he said, adding that the war will be costly, “but less costly than for us to be slaughtered like sheep.”