Iranian President Hassan Rouhani warned Thursday that he was facing domestic opposition to a landmark nuclear deal with major powers that is to go into effect next week.

Rouhani, whose June election has led to a quickening rapprochement with the West after years of hostility, said there was organised opposition in Iran to his efforts to allay Western concerns about its nuclear programme in return for an easing of sanctions.

"A group does not wish to see the sanctions lifted," the president said in remarks reported by the Tasnim news agency.

"This group -- for their individual and party interests -- is against the normalisation of relations with the world."

During a visit to the UN General Assembly in New York in September, Rouhani held a historic telephone call with US President Barack Obama ending decades of estrangement between the two governments.

On his return, he was greeted by cheering supporters of his efforts to end US and EU sanctions that have crippled Iran's economy but he was also met with shoe-throwing by hardline protesters.

Rouhani already went on the defensive Wednesday in the runup to next week's start of implementation of the November deal under which Iran agreed to suspend its enrichment of uranium to levels that have worried the West and address concerns about its existing stockpiles.

On Thursday, speaking on a tour of southwestern Khuzestan province, a key oil producing region on the border with Iraq which has a large ethnic Arab community, Rouhani said his opening to the West was a vital national interest but that it would take time.

"We want to cut the sanction ropes that have entangled our movement... It will not happen overnight," he said.

"This must be achieved step by step and is a very difficult task."

Rouhani acknowledged that the interim deal he struck with the P5+1 group of Britain, China, France, Russia and the United States plus Germany would not spell an immediate end to sanctions while negotiations on a comprehensive deal continue over the next six months.

"It is correct that the structure of sanctions remains in place.. but we have taken down one or two of its pillars," he said.