Six mortar shells landed near a remote Saudi border post close to neighbouring fellow oil producers Iraq and Kuwait on Wednesday, but caused no damage, the kingdom said on Thursday.

The shells hit desert on the far northwestern fringes of the kingdom's oil producing region and several hundred kilometres (miles) from its top fields, source of the world's largest oil exports and heart of the largest Arab economy.

"Six mortar shells fell in an uninhabited area near the new Al-Auja border guard centre of Hafr Al-Batin in the Eastern Province. Thank God no damage resulted from it," said General Mohammed al-Ghamdi, the border guard media spokesman, in a statement carried by the official Saudi Press Agency.

Ghamdi said he had been in contact with border guards of "neighbouring countries" to take necessary measures to determine the source of mortar fire and prevent it recurring.

Saudi news website sabq.org published photographs showing what it said were small craters in the desert caused by the impact of the shells. A high barbed wire fence and a road could be seen in some of the pictures.

The kingdom has constructed a barricade of fences along its Iraqi border.

Saudi Arabia's Eastern Province shares around 60 km (38 miles) of border with Iraq near the town of Hafr Al-Batin. The border area is deep in the desert, with no towns or villages nearby. The province also borders Kuwait.

Saudi Arabia has significant 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 located much further to the southeast, hundreds of km away. -Reuters