Saudi Arabia's Foreign Minister Adel al-Jubeir speaks at a briefing with reporters at the Saudi Embassy in London, Britain September 5, 2017. REUTERS/Hannah McKay

LONDON (Reuters) - Saudi Arabia supports U.S. President Donald Trump’s stance on Iran after he decided not to certify that Tehran is complying with a nuclear accord, Saudi Foreign Minister Adel al-Jubeir said on Tuesday.

U.S. President Donald Trump broke ranks with other major powers this month by refusing to formally certify that Tehran is complying with the deal, even though international inspectors say it is.

Jubeir said the nuclear deal had shortcomings, and that he agreed with Trump’s assessment that Iran was working to destabilise the region and was funding militant organisations.

Sunni Muslim Saudi Arabia, a U.S. ally, has been at loggerheads with Iran, a Shi’ite Muslim country, for decades, and the countries have fought a long-running proxy war in the Middle East.

“(Iran’s behaviour) is not acceptable, and there will be consequences to the Iranians. This is what President Trump has said, and we are very supportive of that,” Jubeir said at a conference in London.

Following Trump’s decision, U.S. Congress has until mid-December to decide whether to reimpose economic sanctions on Tehran that were lifted under the pact.

Jubeir said that new sanctions on Iran would be welcome, and that a delay could mean that by the time sanctions had impact, Iran could have already developed “a dozen” nuclear bombs.

“The international community needs to support those (sanctions) in order to send a very strong message to Iran that your behaviour, your nefarious activities, have consequences,” Jubeir said.

Iran says its nuclear programme is for peaceful purposes and denies it has aimed to build an atomic bomb.