ISLAMABAD: Pakistan on Monday expressed serious concern over the recent escalation of tension between Saudi Arabia and Iran over the former's execution of a Shia cleric on terror charges, calling for a peaceful resolution of all issues, Radio Pakistan reported.

In a statement, the Foreign Office said Pakistan believes in peaceful co-existence and wants a solution to the current crisis since "terrorists benefit from differences between the Muslim Ummah."

Pakistan also condemned the attack on the Saudi Embassy in Tehran and termed the incident 'unfortunate'.

Saudi Arabia executed Nimr and three other Shias on terrorism charges Saturday, alongside dozens of Sunni militants. Shia Iran hailed Nimr as a “martyr” and warned Saudi Arabia's ruling Al Saud family of “divine revenge”.

Shia groups united in condemnation of Saudi Arabia while Sunni powers rallied behind the kingdom, hardening a sectarian split that has torn apart communities across the Middle East and nourished the jihadist ideology of Islamic State.

Al-Azhar, the Cairo-based seat of Sunni Muslim learning, and the Organisation of Islamic Cooperation in Saudi Arabia, condemned the attacks on Riyadh's missions and stressed Tehran's obligation to respect the internal affairs of the kingdom.

The UAE, an ally of Saudi Arabia that is also home to hundreds of thousands of Iranians, cut the number of Iranian diplomats allowed in the country, after summoning the ambassador to protest what it called Iran's interference in Saudi Arabia.

The Yemeni government on Monday announced a curfew in the port city of Aden, a beach-head for Saudi and UAE forces waging war on the Shia Houthi group that controls much of the country. A ceasefire collapsed on Saturday.

Western powers, many of which supply billions of dollars worth of weaponry to Gulf Arab powers, tried to tamp down the tensions with Iran but also deplored the executions, as human rights groups strongly criticised Saudi Arabia's judicial process and protesters gathered outside Saudi embassies.

Related: Mass execution: Saudi Arabia beheads 47 on terror charges in one day