US Secretary of State Hillary Clinton on Sunday urged Arab states in the Gulf to stay focused on sanctions against Iran over its controversial nuclear programme, at the start of a regional tour.

Speaking on her plane as it landed in Abu Dhabi, Clinton advised caution when asked about new Israeli estimates suggesting Iran would take longer to acquire the capacity to build a nuclear bomb than previously feared.

"We don't want anyone to be misled by anyone's intelligence analysis," Clinton told reporters.

"We expect all of our partners who share that concern (over Iran)... to stay as focused as they can and to do everything within reason that will help to implement these sanctions," she said.

"Now we do keep the pressure on all the time because the Iranians are always looking for a way out of the impact of the sanctions," she said.

But she said Gulf countries, which have close economic ties with Iran, have been "very responsive" to enforcing sanctions.

On December 29, Israel's strategic affairs minister, Moshe Yaalon, said the Islamic republic's nuclear programme had been beset by difficulties, leaving Tehran still about three years away from being able to build nuclear weapons.

"The timeline is not so important as the international effort to try to ensure that whatever the timeline Iran is not pursuing nuclear weapons," Clinton said.

"I don't know that it gives much comfort to somebody who is in the Gulf or is in a country that Iran has vowed to destroy that it's a one-year timeline or a three-year timeline," she said.

Israel, which has the Middle East's sole if undeclared nuclear arsenal, regards Iran as its principal threat, after repeated predictions by hardline President Mahmoud Ahmadinejad of the Jewish state's demise.

Along with the West, Israel suspects Iran of trying to develop atomic weapons under the guise of a civilian nuclear programme, a claim Tehran denies.

Israel has backed US-led efforts to prevent Iran from developing a nuclear weapons capability through sanctions, but it has also refused to rule out military force.

Under US pressure, the UN Security Council last June imposed a fourth round of sanctions against Iran in a bid to halt its uranium enrichment programme.

US President Barack Obama's administration says it believes that the sanctions are "beginning to bite" and have helped to force Iran to return to negotiations over its nuclear ambitions.

Host Turkey said a new round of talks involving Iran and Britain, China, France, Germany, Russia and the United States will take place in Istanbul on January 21 and 22.

A previous round between Iran and the six world powers in Geneva on December 6 and 7 ended without any sign of progress.

In her five-day trip to the United Arab Emirates (UAE), Oman and Qatar, Clinton said she would also urge the region to cooperate more to advance democratic, economic and social reforms.

The stalled Palestinian-Israeli peace process and Iraq will also be on the agenda as Clinton visits Abu Dhabi on Monday, the UAE commercial hub of Dubai on Tuesday, Muscat on Wednesday, and Doha on Wednesday and Thursday.

As with the preceding administration of George W. Bush, Obama's team is urging Sunni Arab allies in the Gulf to overcome what it sees as lingering reservations and build closer ties with the new Shiite-led Iraq.

Obama on Tuesday congratulated Iraq after its parliament endorsed a new government led again by Shiite Prime Minister Nuri al-Maliki, saying the move was a "significant" historic moment and represented a rejection of extremism.

Washington sees the new government -- finally formed after elections in March -- as more broadly representing Iraq's people, including the Sunni minority which dominated the country under Saddam Hussein and his predecessors.

"I'd like to see every (Gulf) country open an embassy (in Iraq). I'd like to see normal relations. I'd like to see the leaders of Iraq invited and consulted," Clinton said on the plane.

She said she expected Iraq's reintegration into the region to be an item on the agenda of the Gulf Cooperation Council (GCC) when she visits Doha. The GCC is made up of Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the UAE.

US officials said Kuwait, Bahrain and the UAE had posted ambassadors in Iraq, but Qatar, Oman, Saudi Arabia and Yemen have no diplomatic mission there.