A military court in the Gaza Strip has sentenced a Palestinian to death for collaborating with Israel and another to life with hard labor, the Hamas interior ministry said on Thursday.

The 43-year-old, identified only by his initials AH, "has been sentenced to capital punishment for acts of collaboration wit the occupation", a ministry statement said.

U.S. Secretary of State John Kerry on Thursday admitted there was skepticism and cynicism about his efforts to broker new talks between Israelis and Palestinians, as he made his fourth visit to Israel.

Flying in from a night of diplomacy in Amman over the war in Syria, Kerry went straight into talks with Prime Minister Benjamin Netanyahu as he pursued his bid to kick-start negotiations frozen since late 2010.

Middle East unrest increases the chance of Israel becoming embroiled in a surprise war, the head of its air force said on Wednesday.

"When you look (around) today I think that a surprise war can be born in very many configurations," Major General Amir Eshel told a conference near Tel Aviv in remarks broadcast on local television and radio.

Israel's ability to deter attack on its positions in the occupied Golan Heights remains undiminished despite an uptick in fire from the Syrian side of the ceasefire line, a defense official said on Wednesday.

"The good news is that the continued stability of the Golan Heights (and) the deterrent power of the Israeli army have not been weakened," senior defense adviser Amos Gilad told army radio.

Israel arrested three Palestinian police officers on Wednesday after they returned to duty having served jail terms in Palestinian prisons for shooting dead a Jewish settler, a Palestinian official said.

"Israel arrested three elements of the national security who had been detained by the Palestinian Authority in Al-Jneid prison in Nablus for their unintentional killing of a settler two years ago," the Palestinian official told Agence France Presse.

The head of Israel's armed forces warned Syrian President Bashar Assad on Tuesday of "consequences" if fire continues from Syrian territory against Israeli troops in the occupied Golan Heights.

"If he disturbs the Golan Heights, he will have to bear the consequences," Lieutenant General Benny Gantz said in an address at Haifa University and broadcast on Israeli television.

Israel's Shin Bet domestic spy agency said on Tuesday it had foiled planned attacks on Israelis by two Palestinian Islamist groups in the Hebron area.

It said that, in March, Shin Bet, army and police uncovered a nine-man Hamas cell in the village of Bani Naim, south of the West Bank city, which planned to shoot dead an Israeli settler working in nearby fields.

The European Union stands poised to put the military wing of Hizbullah on its list of terrorist organizations after a formal request to blacklist the group was filed by a member state Monday, diplomats said.

The request from Britain formally launches a process to blacklist the group, a move that has long been requested by Israel and which will be discussed in early June, several EU diplomats told Agence France Presse.

Syria's army destroyed an Israeli military vehicle which it said had crossed the sensitive ceasefire line in the Golan Heights on Tuesday, the military said in a televised statement.

"Our armed forces have destroyed an Israeli vehicle with everything that it had in it... The vehicle had crossed the ceasefire line and was moving towards the village of Bir Ajam, situated in the liberated Syrian zone" of the Golan, it said.

Secretary of State John Kerry was returning to the Middle East Monday, aiming to shore up peace efforts as he seeks to help end the Syria war and coax Israel and the Palestinians back to talks.

The new top U.S. diplomat -- making his fourth visit to Israel in a little over three months -- left Andrews Air Force Base in Maryland, first headed for key Gulf ally Oman, which also maintains close ties to Iran.