WASHINGTON (AFP) - US President Barack Obama spoke with his Chinese counterpart Xi Jinping to thank him for Beijing's work on the deal to curtail Iran's nuclear programme, the White House said Tuesday.

In a conversation on Monday, the two leaders also agreed it was important to keep working together to ensure implementation of the historic accord reached last week in Vienna, the White House said in a statement.

Obama also reiterated he was looking forward to welcoming Xi to Washington for a state visit in September.

China was one of the so-called P5+1 countries - along with Britain, France, Germany, Russia and the United States - that spent nearly two years negotiating with Iran in a gruelling process that finally yielded the agreement.

The accord is designed to curtail Iran's nuclear program and prevent it from developing nuclear weapons in exchange for the lifting of international sanctions that have hit the Iranian economy hard.

While the United States and China have worked together on the Iran dossier, they are at odds on other matters including cyber-hacking and Beijing's territorial claims in the South and East China Seas.