By Angus McDowall
RIYADH (Reuters) - Six mortar bombs landed near a remote Saudi border post close to neighboring fellow oil producers Iraq and Kuwait, but caused no damage, Saudi Arabia said on Thursday, a day after the incident.
The mortar rounds hit desert on the far northwestern fringes of the kingdom's oil-producing region and several hundred kilometers (miles) from the major fields operated by the world's largest oil exporter and biggest Arab economy.
There was no word on who was behind the barrage, which occurred two days after twin suicide bombings killed 25 people near Iran's embassy in Beirut. Some Shi'ite commentators blamed the assault on Saudi Arabia, which has condemned the attack.
Saudi Interior Ministry spokesman Major-General Mansour Turki said Iraq and Kuwait, as well as the kingdom itself, were investigating the mortar fire. Baghdad said it was not involved.
"There were no rockets or anything fired towards the Saudi border by security forces," said Jabar al-Sa'adi, head of Basra provincial council's security committee, in southern Iraq.
Turki said Saudi forces had not been put on higher alert after the so far unexplained bombardment.
"This is an area very close to the Iraqi and Kuwaiti borders. So sometimes this could come from military training or many other reasons. We have to wait for the investigation to show where it happened," he said.
Saudi news website sabq.org published pictures of small craters in the desert which it said the mortar fire had caused. A high barbed-wire fence and a road were visible in some photos.
"Six mortar rounds fell in an uninhabited area near the new al-Auja border guard center of Hafr al-Batin in Eastern Province. Thank God, no damage resulted," border guard spokesman General Mohammed al-Ghamdi told the official Saudi Press Agency.
He said he had contacted his counterparts in neighboring countries to locate the source of the firing and prevent any recurrence.
Sunni Muslim Saudi Arabia, a close ally of Kuwait, has tense relations with the Shi'ite-led Iraqi government, which it views as a pawn of its main regional rival Iran. It has not had an ambassador based in Baghdad since before the 1990-91 Gulf crisis.
Sectarian fighting in Iraq since the U.S.-led invasion in 2003 has involved Sunni militants close to al Qaeda as well as Shi'ite militias which have no love for Saudi Arabia.
Some Iraqi Shi'ites support Syrian President Bashar al-Assad in his 2-1/2-year-old struggle to crush what has become an armed revolt by mainly Sunni rebels, some of them backed by Riyadh.
The conflict has aggravated Sunni-Shi'ite antagonism across the region, not least in Syria's smaller neighbor Lebanon, where Iran and Saudi Arabia have long vied for influence.
A Lebanon-based Sunni group linked to al Qaeda has claimed responsibility for the Iran embassy attack in Beirut.
The Saudi border area with Iraq and Kuwait lies deep in a largely unpopulated desert. The kingdom has installed fences along its long frontier with Iraq, about 60 km (38 miles) of which runs along the edge of Eastern Province, which is home to many of Saudi Arabia's own substantial Shi'ite minority.
The kingdom has oil facilities in the Neutral Zone it shares with Kuwait, more than 100 km (62 miles) from Hafr al-Batin, but its main oil and gas fields are much further to the southeast.
(Additional reporting by Sylvia Westall in Baghdad,; Editing by William Maclean and Alistair Lyon)