By Arshad Mohammed
MONTREUX, Switzerland (Reuters) - U.S. Secretary of State John Kerry quietly cautioned Israel not to undercut nuclear negotiations with Iran that resumed on Monday as Israeli Prime Minister Benjamin Netanyahu prepared to make the case in Washington against the diplomacy.
Kerry and Iranian Foreign Minister Mohammad Javad Zarif met for about 90 minutes on the first of what could be three days of talks in the Swiss lakeside town of Montreux on curbing Iran's nuclear program in exchange for relief from economic sanctions.
The two men, along with U.S. Energy Secretary Ernest Moniz and Iranian atomic energy chief Ali Akbar Salehi, shook hands and then met for about 50 minutes on Monday afternoon, followed by a second session of about 40 minutes.
Both sides postured in advance and suggested the other would be to blame if the talks fail to meet an end-March deadline for a framework accord. Kerry said Iran must be prepared to compromise and Zarif called for the total lifting of sanctions imposed on the Islamic Republic as part of any final deal.
Speaking to reporters in Geneva before the meeting, Kerry struck a balance between defending Israel before the U.N. Human Rights Council, which Washington has long accused of anti-Israel bias, and also suggesting the Israelis not undermine the talks.
"We are concerned by reports that suggest selective details of the ongoing negotiations will be discussed publicly in the coming days," he said, apparently alluding to Netanyahu's planned speech on Tuesday before the U.S. Congress.
"Doing so would make it more difficult to reach the goal that Israel and others say they share in order to get to a good deal," Kerry said. "Israel's security is absolutely at the forefront of all of our minds, but frankly so is the security of all of the other countries in the region. So is our security."
Netanyahu says he fears U.S. President Barack Obama's Iran diplomacy could allow Israel's arch Middle East adversary to develop atomic weapons. U.S. officials say the best way to prevent that outcome is a negotiated settlement.
Washington and some allies, notably Israel, suspect Iran has used its civilian nuclear program as a cover to develop a nuclear weapons capability. Iran denies this, saying its program is for peaceful purposes such as generating electricity.
Netanyahu's main aim is to warn U.S. lawmakers about the risks of a deal with Iran and to keep alive the possibility of Congress passing new sanctions, a step critics say could scuttle the talks and raise the risk of war. Critics also suspect him of seeking political gain before Israel's March 17 election.
In a speech to the powerful pro-Israel lobby group AIPAC in Washington on Monday, Netanyahu said the nuclear deal being negotiated could threaten Israel's survival and said he had a "moral obligation" to speak up about the issue.
U.S. officials have offered equivocal assessments of where they are in the talks with Iran that involve five other major powers: Russia, China, Britain, France and Germany. They have set an end-June deadline for a final detailed settlement.
"We have made some progress but we still have a long way to go and the clock is ticking," Kerry told reporters before driving to Montreux. "We're going to find out whether or not Iran is willing to make the hard choices that are necessary."
Kerry said a vital component would be a rigorous international inspection regime to ensure Iran was not seeking nuclear weapons, saying the Islamic Republic already has the knowledge to make fissile material.
"You can't bomb knowledge into oblivion unless you kill everybody," he said. "You can't bomb it away."
Zarif put the onus on the United States and its partners to lift sanctions to achieve a deal. "If they want an agreement, sanctions must go ... We believe all sanctions must be lifted," Zarif told reporters in Geneva.
One of the disputes holding up a final agreement is over the pace at which sanctions should be dismantled. Tehran wants them rapidly removed while Western powers want gradual steps responding to Iranian performance in implementing the accord.
(Additional reporting by Stephanie Nebehay in Geneva, Matt Spetalnick and Emily Stephenson in Washington; Editing by Mark Heinrich and Gareth Jones)