Interpol said Friday it will make a new push to help Bulgaria identify the bomber who killed six people, including five Israeli tourists, at Burgas airport in July.

"Interpol plans on re-issuing the image (of the suspect), reminding people, asking people, hoping that maybe we will catch someone who is watching TV or on the Internet, who recognizes the person and can help give leads to identifying him and locating him," said the chief of the global policing body, Ronald Noble.

Thousands of angry Palestinians rallied across the West Bank on Friday, urging Hamas militants to "bomb Tel Aviv" as Israel pursued a relentless air campaign on the Gaza Strip.

More than 1,000 protesters gathered in central Ramallah, shouting slogans of support for Gaza's Hamas rulers, and waving the Islamist movement's green flag, Agence France Presse correspondents said.

German Chancellor Angela Merkel on Friday called on Cairo to use its influence on Hamas to ease tensions in the Gaza Strip as Egyptian Prime Minister Hisham Qandil visited the violence-wracked area.

"The federal chancellor calls on the Egyptian government to use its influence on Hamas to push it towards a moderation of the violence," Merkel's deputy spokesman Georg Streiter told a regular government news conference.

European Union foreign policy chief Catherine Ashton said Friday that Israel had the right to protect its people against Gaza rocket attacks but urged it to stick to a "proportionate" response.

Deploring the loss of civilian lives on both sides, Ashton said in a statement that "the rocket attacks by Hamas and other factions in Gaza which began this current crisis are totally unacceptable for any government and must stop."

Egyptian Prime Minister Hisham Qandil vowed Friday to intensify Cairo's efforts to secure a truce and end Israel's "aggression" in the Gaza Strip.

"Egypt will not hesitate to intensify its efforts and make sacrifices to stop this aggression and achieve a lasting truce," he said at a press conference in Gaza City's Shifa hospital after seeing some victims from the latest Israeli strike.

Gaza fighters fired rockets at both Jerusalem and Tel Aviv on Friday aiming for the Jewish state's political and commercial hearts, prompting Israel to call up thousands more reservists in readiness for a potential ground war.

The military wing of the Islamist Hamas movement which rules Gaza said it fired the rocket at Jerusalem, the first to strike the outskirts of the Holy City in the history of the Israeli-Palestinian conflict.

Saudi King Abdullah has called for reason and wisdom during a telephone conversation with Egyptian President Mohammed Morsi in which he discussed the latest clashes between Gaza and Israel, state news agency SPA reported.

The monarch, whose country is a heavyweight in the six-nation Gulf Cooperation Council, told Morsi "that things must calm down and reason and wisdom must reign over passionate reactions," SPA said late on Thursday.

The Israeli army started calling up 16,000 reservists on Friday, as officials said the Jewish state was preparing for a possible ground offensive into the Gaza Strip.

"They're distributing emergency call-up notices now, the process has started," an army spokeswoman told Agence France Presse.

Israeli Defense Minister Ehud Barak on Thursday approved the call-up of 30,000 reserve soldiers, who can be called into action by the military at any point, the army's official spokesman said.

"We are in the process of expanding the campaign," Brigadier General Yoav Mordechai told Channel 2 television as Israel pressed a massive air campaign against Gaza militants.

Russian President Vladimir Putin on Thursday urged both Israeli Prime Minister Benjamin Netanyahu and the Palestinians to avoid escalating Gaza violence that has killed 15 Palestinians and three Israelis.

"The president of Russia called on the parties to exercise restraint and avoid the path of escalating violence, whose victims include civilians, and to do everything to return the situation to its normal course," the Kremlin said following a telephone conversation between Putin and Netanyahu.