Turkey's government has urged Saudi Arabia and Iran to calm their diplomatic row, saying the dispute will only worsen regional tensions.

Deputy PM Numan Kurtulmus said the Middle East was "already a powder keg".

He criticised attacks on Saudi missions in Iran but also Saudi Arabia's execution of a Shia Muslim cleric, which triggered the dispute.

Saudi Arabia has broken off diplomatic relations with Iran and is cutting trade and air links.

On Monday, some of Riyadh's allies joined diplomatic action against Iran.

The US has also called on both countries to calm the escalating row.

Saudi Arabia and Iran are respectively the key Sunni Muslim and Shia powers in the region and back opposing sides in Syria and Yemen.

"We want both countries to immediately move away from the situation of tension that will obviously only add to the already severe tensions existing in the Middle East," Kurtulmus was quoted as saying by the Anatolia news agency.

"The region is already a powder keg. Enough is enough. We need peace in the region."

He called on Iran to protect all diplomatic missions and said that Turkey was against "all instances of capital punishment especially when it is politically motivated".

"For us it is not possible to support capital punishment by any country," he added.

"Saudi Arabia and Iran are our friends and we don't want them fighting because that's the last thing this region needs."

SUNNI-SHIA DIVIDE

--The split arises from a dispute soon after the death of the Prophet Muhammad in 632 over who should lead the Muslim community

--Sunnis are estimated to make up between 85% and 90% of Muslims

--Though the two branches have co-existed for centuries and share many fundamental beliefs and practices, differences lie in the fields of doctrine, ritual, law, theology and religious organisation

On Saturday, Saudi Arabia executed cleric Sheikh Nimr al-Nimr and 46 others after they were convicted of terror-related offences.

The move prompted an angry reaction from Iran. Protesters set fire to the Saudi embassy in Tehran and a consulate in the city of Mashhad before being driven back by police.

Saudi Arabia announced late on Sunday that it was cutting diplomatic relations with Iran after the storming of the embassy in Tehran.

It said all commercial and air traffic links were being cut and that Saudi citizens were banned from travelling to Iran.

Saudi UN ambassador Abdallah al-Mouallimi said on Monday that the dispute could be resolved if Iran stopped "interfering in the affairs of other countries, including our own".

Riyadh has previously accused Iran of interfering in Arab affairs.

Speaking in New York, Mouallimi said peace efforts in Syria and Yemen should not be affected by the spat but criticised Iran's contribution to the process.

"The Iranians even before the break of diplomatic relations have not been very supportive, not very positive in these peace efforts," he said.

"They have been taking provocative and negative positions... and I don't think the break in relations is going to dissuade them from such behaviour."

Bahrain and Sudan also severed relations with Iran on Monday, and the UAE has downgraded its diplomatic team.

Bahrain, which is ruled by a Sunni monarchy but has a majority Shia population, gave Iranian diplomats 48 hours to leave the country.

The Sudanese foreign ministry said its action was on response to "the barbaric attacks on the Saudi Arabian embassy in Tehran and its consulate in Mashhad".

On Monday, a White House spokesman called on both countries to "show some restraint and to not further inflame tensions that are on quite vivid display in the region".

But Iran's foreign ministry accused the Saudis of "continuing the policy of increasing tension and clashes in the region".

The row also affected global markets, sending oil and gold prices higher on Monday.