By Patricia Zengerle
WASHINGTON (Reuters) - Hundreds of U.S. lawmakers pressed Secretary of State John Kerry to lean harder on Iran in talks over its nuclear program in a letter released on Thursday after Israel warned Washington not to go easy on Tehran.
Three hundred and fifty-four members - four-fifths - of the U.S. House of Representatives signed the letter sent to Kerry on Wednesday night, expressing concerns that an agreement on Iran's nuclear program might not require sufficiently strict inspections of its nuclear facilities.
The U.N. nuclear watchdog said on Sept. 5 that Iran had failed to address concerns about suspected atomic bomb research by an agreed deadline.
Israeli Prime Minister Benjamin Netanyahu told President Barack Obama on Wednesday that he must make sure any final nuclear deal with Iran does not leave it at the "threshold" of being able to develop nuclear weapons.
Netanyahu has been attempting to shift the global spotlight away from Islamic State fighters in Iraq and Syria and back to Iran, warning that a nuclear-armed Tehran would pose a far greater threat than the militant Islamists.
Although Israel backs Obama's efforts to forge a coalition to confront Islamic State fighters, some Israelis fear world powers could go easy on Shi'ite Muslim Iran's nuclear program so it will help in the fight against the Sunni Islamists.
Iran and six world powers are expected to meet again for nuclear talks in Europe in the next two weeks, Iranian and Western officials said.
(Reporting by Patricia Zengerle, additional reporting by Lou Charbonneau at the United Nations and Matt Spetalnick in Washington; editing by Andrew Hay)