Israeli Prime Minister Benjamin Netanyahu defended Thursday his high-profile campaign to defeat the Iran nuclear deal after President Barack Obama secured enough backing to keep Congress from blocking it.

Netanyahu has repeatedly spoken out strongly against the agreement between Iran and six major powers aimed at rolling back the Islamic republic's nuclear programme, even appearing before Congress in March.

On Wednesday, Obama earned sufficient backing in Congress to uphold his veto should lawmakers pass a resolution that disapproves the deal.

Netanyahu, whose political opponents accuse him of damaging Israel's relationship with its key US ally, said Thursday it had been important for him to highlight the Jewish state's concerns.

The right-wing prime minister has regularly argued that the deal would not block Iran's path to nuclear weapons.

He has also said that lifting sanctions under the agreement would allow Iran to further back proxy militants in the Middle East, including Israeli enemies Hezbollah and Hamas.

"It's important to reach American public opinion with the fact that Iran is the US's enemy -- it announces that openly -- and Israel is an ally of the US," Netanyahu said.

"This understanding has important ramifications on our security's future," he told foreign ministry employees.

On Wednesday, US Senate Democrat Barbara Mikulski announced her support, giving the deal 34 backers in the 100-member Senate -- the magic number needed to uphold a certain Obama veto should Congress pass a resolution against the deal.

Netanyahu's campaign against the deal worsened his already strained relations with Obama.

In his Thursday remarks, Netanyahu noted "the close connections we have with traditional states, first and foremost the United States, even in the face of disagreements - and those exist."

Isaac Herzog, leader of the opposition Labour party, said that while he thought the deal was bad, once it was done, Netanyahu should have switched focus to Israel's security needs.

The United States currently grants Israel some $3 billion (2.7 billion euros) in military aid yearly outside of spending on other projects, such as assistance in developing the country's Iron Dome missile defence system.

There has been talk of further assistance to compensate for Israel's concerns related to the deal.

"Netanyahu is continuing to bear a grudge instead of working with the Americans on the big issues (of security) -- and in the end, the ones to pay the price will be us," Herzog told army radio.

Israel is believed to be the only country in the Middle East with atomic bombs, although it has never confirmed it.

Iran leader says nuclear deal rests on lifting sanctions
Tehran (AFP) Sept 3, 2015 - Iranian supreme leader Ayatollah Ali Khamenei warned anew Thursday that there could be no nuclear deal with the West if sanctions imposed on Tehran are not lifted.

Khamenei, who has the last say in matters of policy, also said he believes Iran's parliament (majlis) should make up its own mind about landmark July 14 deal struck with six world powers.

"I believe... that it is not in the interest of the majlis to be sidelined," Khamenei said.

"I have no recommendation for the majlis on how it should examine it; it is up to the representatives of the nation to decide whether to reject or ratify it".

Khamenei's comments, published on his personal website, come as a debate rages in Iran over whether the majlis should ratify or reject the deal.

Most US lawmakers oppose it, but President Barack Obama has enough backers in the Senate to uphold his certain veto of any congressional resolution disapproving it.

The majlis announced in mid-August the makeup of a 15-member panel largely composed of conservative lawmakers to review the historic deal.

But the government and the deal's negotiators believe a parliamentary vote is not in the best interest of Iran, arguing that it would transform a voluntary promise made by Tehran into a legal obligation.

Iran's parliament and the US Congress need to vote -- in the coming weeks -- on the agreement struck in Vienna before it can be implemented.

But formal oversight of the accord rests with Iran's Supreme National Security Council, a powerful committee headed by President Hassan Rouhani, which reports to Khamenei.

Khamenei, who has said in past weeks that the fate of the nuclear deal remains unclear, insisted Thursday that if decades of "sanctions are not lifted, then there will be no deal."

He noted that some "American officials speak very badly" of the agreement, without identifying anyone by name.

"If the framework of sanctions are to be maintained, then why did we negotiate," he asked.

On Wednesday, US Secretary of State John Kerry said Iran will be required to live up to the agreement in full before its starts benefitting from sanctions relief.

The deal between Iran and Britain, China, France, Germany, Russia and the United States aims to curb Tehran's nuclear drive in exchange for a gradual lifting of sanctions imposed on its economy since 2006.