Tens of thousands of mainly Shi'a have joined a march in Bahrain to denounce proposals for closer unity between the Sunni-ruled kingdom and neighboring Saudi Arabia.
Protesters chanted "Bahrain is not for sale," as they marched outside the capital, Manama.
Sunni Gulf Arab leaders earlier this week delayed any decision on the plan.
In predominantly Shi'ite Iran, state-run media said thousands of people also took part in protests denouncing the proposed union.
An influential cleric, Ayatollah Kazem Sediqi, in a sermon broadcast live denounced the plan as an "ill-fated plot."
Bahrain has seen intermittent protests led by its Shi'ite majority for more than a year, demanding that the ruling royal family improve human rights and make political reforms.
Iran has repeatedly voiced support for the protests.
Based on reporting by AFP, Reuters, and AP