Rocket kills 1 in Israel while EU top diplomat in Gaza

It was the first strike from the territory to cause any fatalities since the end in January 2009 of Israel's Gaza war.

An hour before the attack, the EU's top diplomat, Briton Catherine Ashton, crossed into the Gaza Strip to tour U.N. facilities and see how the international funding was being used.

A previously unknown Gaza group, Ansar al-Sunna, claimed responsibility for the attack, launched a day before the international Quartet of Middle East peace mediators was to meet in Moscow to discuss ways to revive Israeli-Palestinian talks.

Similar strikes since the Gaza war have been met by Israeli air raids against militants or suspected weapons-producing facilities, but the death of the Thai worker, in Netiv Ha'asara, an agricultural community, may harden Israel's response.

"This is a crossing of the red line, which Israel cannot accept. The Israeli response will be appropriate. It will be strong," Vice Prime Minister Silvan Shalom told reporters.

At a Gaza news conference after the attack, Ashton said: "I condemn any kind of violence, we have got to find a peaceful solution to the issues and problems."

U.N. Secretary General Ban Ki-moon also expressed his condemnation, saying in a statement: "All such acts of terror and violence against civilians are totally unacceptable and contrary to international law."

The incident could have more of an impact on internal Palestinian politics than on the Middle East peace process, which Hamas has refused to join and which is at an impasse over Israeli settlement policy on land Palestinians want for a state.

Hamas Islamists, who seized the Gaza Strip in 2007, had been urging other militant groups not to mount attacks on Israel, voicing concern about retaliation.

SECURITY CHALLENGE

But it has been faced with a mounting security challenge -- including bombings against Hamas officials and facilities -- by Gaza militant groups sharing the hardline ideology of al Qaeda.

A known figure in the hardline Salafist movement, whose agenda of "jihad," or holy war, against the West is contrary to Hamas's nationalist goals, said Ansar al-Sunna was a newly established group.

"The Jihadist mission came in response to the Zionist assaults against the Ibrahimi and al-Aqsa mosques and the continued Zionist aggression against our people in Jerusalem," Ansar al-Sunna said in a statement.

It appeared to be referring to Israel's national heritage plan to renovate holy sites, including the West Bank town of Hebron's Tomb of the Patriarchs that is revered by Muslims and Jews, and the rededication this week of an 18th-century synagogue in Jerusalem, some 400 metres (yards) from al-Aqsa.

In a statement on the rocket firing, Hamas steered clear of comments that could be seen by Palestinians in the Israeli-blockaded Gaza Strip as disapproving of a strike against its enemy, even an attack that strained an informal truce.

"The government of the Zionist enemy, which has launched a war against the Palestinian people and against holy sites and al-Aqsa mosque, bears the responsibility for all the escalation," Hamas spokesman Fawzi Barhoum said.

Palestinian militants in Gaza have carried out sporadic rocket and mortar bomb attacks on Israel since the end of the three-week Gaza war, usually without causing any casualties.

More than 1,400 Palestinians, including hundreds of civilians, were killed in the three-week offensive that was launched with the declared aim of curbing rocket attacks. Thirteen Israelis, among them three civilians, were killed.

(Writing by Jeffrey Heller; Additional reporting by Nidal al-Mughragbi; Editing by Louise Ireland)