Israeli Prime Minister Benjamin Netanyahu warned on Monday that Tehran's nuclear program was getting closer to crossing a crucial "red line" but had yet to reach it.

"It has not yet crossed the red line which I laid out in the United Nations but it is systematically approaching it and we cannot let it cross," he told senior members of his Likud-Beitenu political alliance in remarks broadcast on public radio.

Prime Minister Benjamin Netanyahu told his ministers to keep silent about Syria to avoid the impression Israel is pushing the international community into armed intervention, army radio said Sunday.

Netanyahu gave the instructions after Deputy Foreign Minister Zeev Elkin suggested the international community might react militarily to "take control of the Syrian chemical weapons arsenal".

U.S. Secretary of State John Kerry said Israeli Prime Minister Benjamin Netanyahu had not been able to confirm to him on Tuesday that the Syrian regime had used chemical weapons against rebels.

"I think it is fair to say (the prime minister) was not in a position to confirm that in the conversation," Kerry said, explaining that he had telephoned Netanyahu following reports of their use.

Israeli Prime Minister Benjamin Netanyahu on Sunday vowed Israel would "exact a price" from the Gaza militants who recently fired missiles from Sinai at the southern resort city of Eilat.

"Last week missiles were fired from Sinai at Eilat," Netanyahu said at the start of his weekly cabinet meeting.

Israel's Benjamin Netanyahu has urged caution over international calls to arm Syrian rebels and reserved the right for the Jewish state to block the supply of weapons that could be turned against it.

Speaking to the BBC, the Israeli prime minister said if advanced arms fell into the hands of Islamist militants it could redefine regional security threats.

Israeli Prime Minister Benjamin Netanyahu warned on Tuesday that "tough sanctions" currently imposed on Iran might not be enough to prevent Tehran from obtaining a military nuclear capability.

"We need to stop Iran from acquiring nuclear weapons," he told foreign diplomats attending a reception at the presidential residence in Jerusalem, marking the 65th anniversary of the Jewish state's foundation.

Israeli Prime Minister Benjamin Netanyahu on Sunday said his country's foes will never managed to annihilate Israel, as Tel Aviv marked Memorial Day, remembering its fallen troops and civilian deaths in militant attacks.

"Since our inception as a people, we had to fight for our freedom and our existence," Netanyahu said at a Sunday afternoon ceremony.

Israeli Prime Minister Benjamin Netanyahu said Sunday that Israel cannot rely on any other country, even an ally, when it comes to facing up to the perceived nuclear threat from Iran.

"We appreciate the efforts of the international community to halt Iran's nuclear program," Netanyahu said in a speech on the eve of Holocaust Day.

Israeli troops shot dead two Palestinian youths during a West Bank clash, officials said Thursday, heightening tension ahead of the funeral of a prisoner who died in Israel.

The clashes late on Wednesday in the two of Tulkarem, in the northern West Bank, came after a day of violent protests across the West Bank, where a general strike was called after the death Tuesday of life prisoner Maisara Abu Hamdiyeh in an Israeli jail.

The Israeli army's killing of two Palestinian youths in West Bank clashes jeopardizes U.S. efforts to rekindle peace talks, Palestinian president Mahmoud Abbas said Thursday.

"The Israeli government is behind this escalation," Abbas said in a statement. "The Israeli government is responsible for the (negative) impact on U.S. and international efforts to restart negotiations."