By John Irish and Louis Charbonneau
VIENNA (Reuters) - As a June 30 deadline for a final nuclear deal approaches, major differences remain between Iran and world powers on several key issues including sanctions relief and U.N. access to Iranian sites, a senior Western diplomat said on Friday.
"The most difficult subjects need to be resolved in the coming days," the diplomat told reporters on condition of anonymity in the Austrian capital, where talks between the United States, Britain, France, Germany, Russia, China and Iran have entered their final phase.
"The questions of access and transparency, PMD (possible military dimensions) and sanctions remain extremely problematic," the diplomat added. "We can find an agreement on some points, but on major issues there are still big differences."
Iran and six major powers set themselves an end-June deadline for a long-term deal that would lift sanctions crippling the Iranian economy in exchange for limits on Tehran's nuclear program that would remain in place for at least a decade. But diplomats said the talks would likely run into July.
Senior Iranian negotiator Abbas Araqchi told Iranian reporters that the current negotiations were a "slow and difficult process."
But despite the major obstacles to overcome, a senior U.S. official suggested to reporters on Thursday that an agreement could be within reach.
"Despite these tough issues, here’s really what it’s all about. We can truly see a path forward that gets us to a very good agreement here. We know what the pieces of it are," the official said on condition of anonymity."
Western and Iranian officials say the chances of success in Vienna are greater than the likelihood of failure.
U.S. Secretary of State John Kerry departed for Vienna on Friday, boarding his aircraft from Joint Base Andrews, a military base outside of Washington, with a mechanical lift truck because of his broken leg. He remains on crutches following his May 31 cycling accident.
Iranian Foreign Minister Mohammad Javad Zarif is due to arrive on Saturday morning, when he and Kerry are expected to meet to discuss progress and sticking points in the talks.
The difference on some issues are vast.
Officials close to the talks say they have yet to agree on the speed and scope of lifting sanctions, how Iran will reduce its stockpiles of low enriched uranium, the future scope of Tehran's enrichment-centrifuge research and development program, and access for U.N. inspectors to military and other sites, as well as U.N. access to Iranian nuclear scientists.
Iran rejects allegations from Western powers and their allies that it is seeking the capability to produce nuclear weapons under cover of a civilian atomic energy program.
(Additional reporting by Parisa Hafezi; Editing by Sophie Walker)