Damascus accused Washington and the West on Thursday of seeking to stoke violence in Syria, after U.S. President Barack Obama and European leaders said that Syrian President Bashar al-Assad must step down.

"It is strange that instead of offering (Damascus) a helping hand to implement its program of reforms, the West and Obama are seeking to stoke more violence in Syria," Reem Haddad, the information ministry's director of external relations, told Agence France Presse.

An Israeli air strike on the southern Gaza town of Rafah killed six people on Thursday, Palestinian medics said, just hours after a string of deadly attacks in southern Israel.

Israeli military sources confirmed that air strikes were carried out in Gaza shortly after three attacks in southern Israel killed at least seven people.

President Nicolas Sarkozy of France, Germany's Chancellor Angela Merkel and British Prime Minister David Cameron on Thursday jointly urged Syria's embattled leader Bashar al-Assad to step down.

"We call on him to face the reality of the complete rejection of his regime by the Syrian people and to step aside in the best interests of Syria and the unity of its people," they said in a joint statement.

U.S. President Barack Obama demanded Thursday that Syrian President Bashar al-Assad "step aside" and imposed tough sanctions on Damascus including an asset freeze and ban on U.S. investments in Syria.

"We have consistently said that President Assad must lead a democratic transition or get out of the way. He has not led. For the sake of the Syrian people, the time has come for President Assad to step aside," Obama said.

Switzerland has decided to recall its ambassador to Damascus for consultations in protest at Syria's crackdown on protestors, the foreign ministry said on Thursday.

"The unacceptable behavior of the Syrian security service has led the foreign ministry to recall the ambassador from his post in Damascus for consultations in Bern," the ministry said in a statement.

Seven Israelis were killed in a string of coordinated attacks in southern Israel Thursday, and hours later the Israeli military hit back with angry air raids on Gaza militants it said were responsible.

The bloodshed, which killed six civilians and a soldier on two desert roads near the Red Sea resort town of Eilat, prompted a wave of international condemnation led by the White House.

Libyan rebels pushing to cut off Tripoli claimed on Thursday to have seized a key oil refinery which is a major source of fuel for the capital.

A rebel commander said late Wednesday that his fighters had managed to "gain control of the refinery" in the town of Zawiyah, some 40 kilometers west of Tripoli.

Suspected al-Qaida gunmen have seized control of the town of Shaqra in lawless Abyan province, a stronghold of the jihadist network in southern Yemen, a local official said on Thursday.

"al-Qaida fighters have attacked positions of armed tribesmen" tasked with defending the town on Wednesday, and have "managed to drive them away without any resistance," the official told Agence France Presse.

Turkey's military on Thursday confirmed its warplanes has pounded Kurdish rebel targets during cross-border raids into northern Iraq and vowed to continue the "actions" until the guerrilla group is "rendered ineffective."

A military statement said the jets hit 60 suspected rebel targets on the mountainous region near the border with Turkey late Wednesday as well as targets on Mt Qandil, along the Iraqi-Iranian border, where the leaders of the rebel group Kurdistan Workers' Party, or PKK, are believed to be hiding.

Israeli Foreign Minister Avigdor Lieberman accused Turkish Prime Minister Recep Tayyip Erdogan on Thursday of trying to "undermine Israel's legitimacy" by demanding an apology for the 2010 deadly flotilla raid.

"The Turkish prime minister wants to undermine the legitimacy of the state of Israel by demanding an apology that would constitute an admission of guilt and undermine our right to self-defense against attacks from Gaza," he told public radio.