SAUDI-LED plans for deeper Gulf Arab regional integration to challenge Iran are in doubt after the failure to announce an expected unity deal between Saudi Arabia and neighbouring Bahrain.

Expectations had been running high ahead of a special summit of the six-member Gulf Cooperation Council in the Saudi capital, Riyadh, but a decision was put off until the GCC next meets, in December. Iranian MPs warned that the plans were likely to increase insecurity in the Gulf.

As an initial step, Saudi Arabia and Bahrain had signalled a readiness to announce a bilateral union, but even that limited move failed to materialise.

Prince Saud al-Faisal, the Saudi foreign minister, criticised Iranian “provocations” over three occupied Gulf islands that are claimed by the United Arab Emirates. Threats from Tehran were unacceptable, he warned. Iran is also routinely accused of backing the Shia-dominated opposition in Bahrain.

The GCC secretary-general, Abdullateef al-Zayani, said all six member countries would sign up to a common defence policy when they meet in Manama in December. But the UAE and Oman, whose leaders did not attend the Riyadh summit, appeared to have reservations. Qatar and Kuwait were said to have objections too.

Plans for a Saudi-Bahrain union have been talked up by both governments since last year, when a 1,500-strong Saudi-led GCC force intervened in Bahrain to help crush the pro-democracy protests.

King Hamad of Bahrain said the proposed Gulf union was a “response to changes and challenges that face us on international and regional fronts”. The nature of this union remains unclear but a Bahraini minister said it could follow the European Union model.

The GCC has achieved very little in terms of regional integration in 30 years. Worries about Saudi dominance have already frozen plans for a single Gulf currency. Abdulkhaliq Abdullah, an Emirati analyst, said the six GCC members were “not all enthusiastic” about a union.

Prince Saud told reporters after the summit: “There was no step to have a special relation between Bahrain and Saudi Arabia at this stage, although both countries would welcome a closer association. There is no problem between Bahrain and Saudi Arabia that would prevent closer cooperation. I am hoping that the six countries will unite at the next meeting. The issue will take time.”

The Gulf leaders also discussed the crisis in Syria, where the Saudis and Qataris are leading the anti-Assad camp and have supported arming anti-regime rebels.

The Saudi-Bahrain unity proposal had been angrily denounced by the Bahraini opposition. Sheikh Ali Salman, leader of al-Wefaq, warned that any such move should be subjected to a referendum in all GCC states. Bahraini protesters interpret it as a way to unite the two western-backed Sunni monarchies to work together to crush Shia dissent and confront Iran.

In Tehran, MPs attacked the unity plan. “Bahraini and Saudi rulers must understand that this unwise decision will only strengthen the Bahraini people’s resolve against the forces of occupation,” they said. The letter was signed by 190 of 290 MPs, and warned that “the crisis in Bahrain will be transferred to Saudi Arabia and will push the region towards insecurity”.

Zayani said the GCC had agreed financial support over five years for Jordan and Morocco, the two relatively poor Arab monarchies that are seeking to respond with limited reforms to defuse the tensions and expectations stirred up in the Arab spring.

— The Guardian, London