Israel urged the world to avoid a partial deal with Iran which could see a relaxing of sanctions, as a new round of nuclear talks was launched Tuesday in Geneva.

The security cabinet warned the international community against any "partial agreement that would fail to bring about the full dismantling of the Iranian military nuclear programme...(which) could lead to the collapse of the sanctions regime."

Iran began two days of closed-door negotiations in Geneva on Tuesday with the P5+1 countries -- the United States, Britain, France, China, Russia and Germany, ending a six-month hiatus.

Israeli Prime Minister Benjamin Netanyahu has launched a media blitz in recent days, warning against concessions to Iranian President Hassan Rouhani.

Rouhani's conciliatory tone has raised hopes of a breakthrough in the decade-long dispute over Tehran's nuclear programme.

The security cabinet statement called on world powers to be wary of Iran during negotiations.

"Iran believes it can get by with cosmetic concessions that would not significantly impede its path to developing nuclear weapons, concessions that could be reversed in weeks," the statement said.

"In exchange, Iran demands an easing of the sanctions, which have taken years to put in place."

The security cabinet said the P5+1 should "reject Iran's attempts to reach a deal that would leave it with the capability to develop nuclear weapons."

An Israeli official told AFP that the seven-member ministerial committee had met on Monday night but released the statement Tuesday morning to coincide with the launch of the Geneva talks.

Israel, it said, did not oppose Iran having a peaceful nuclear energy programme -- one which would not require uranium enrichment or plutonium production, it said.

"Iran claims that it supposedly has the 'right to enrich.' But a country that regularly deceives the international community, that violates UN Security Council resolutions ... has no such right," it said.

Later in the day, Netanyahu stressed that "now" was "an opportune moment to reach a genuine diplomatic solution that peacefully ends Iran's military nuclear program."

Speaking ahead of a meeting with Malta Prime Minister Joseph Muscat, Netanyahu said that pressure in the form of sanctions is what brought Iran back to the negotiating table.

"And it is that pressure which makes the peaceful dismantling of Iran's military nuclear programme possible," Netanyahu said in remarks relayed by his office.

But Netanyahu reiterated in parliament that the option of a unilateral Israeli military strike should remain on the table.

"Pre-emptive strikes must not be ruled out," he told MPs.

"Such strikes are not necessarily called for in every case... but there are situations in which thinking about the international response to such a step is not equal to the bloody price we would pay" for the existence of a nuclear-armed Iran.

The Geneva talks are aimed at reaching accord over Iran's nuclear programme, which Israel and the West say is aimed at developing an atomic bomb and Tehran says is for peaceful purposes only.

The Islamic republic has been slapped with several rounds of sanctions because of its nuclear programme.

Israel, the Middle East's sole if undeclared nuclear-armed power, wants Iran to meet four conditions before the sanctions are eased: halting all uranium enrichment; removing all enriched uranium from its territory; closing its underground nuclear facility in Qom; and halting construction of a plutonium reactor.

Israel has refused to rule out military strikes against Iran, with Netanyahu telling the UN General Assembly this month that the Jewish state would act unilaterally if necessary.