(Adds colour, Zarif remark)
* Reporters see melted pipes, scorched towers
* Aramco says it's working 24/7 on repairs
* Riyadh sees strikes as global test of will
* Attacks worsen Saudi, Iranian rivalry in region
By Stephen Kalin and Rania El Gamal
KHURAIS, Saudi Arabia, Sept 20 (Reuters) - Saudi Arabia on Friday took media to inspect oil facilities hit by attacks that Washington and Riyadh blame on Iran, showing melted pipes and burnt equipment, as Tehran vowed wide retaliation if heightened tensions boil over into hostilities.
The kingdom sees the Sept. 14 strikes on its Khurais and Abqaiq facilities -- the worst attack on Gulf oil infrastructure since Iraq's Saddam Hussein torched Kuwaiti oilfields in 1991 -- as a test of global will to preserve international order.
Iran denies involvement in the attack, which initially halved oil output from Saudi Arabia, the world's largest petroleum exporter. Responsibility was claimed by Yemen's Houthi movement, an Iran-aligned group fighting a Saudi-led alliance in Yemen's four-year-old conflict.
At Khurais, which the Saudi defence ministry says was hit by four missiles, Reuters reporters were shown repair work under way, with cranes erected around two burnt-out stabilisation columns, which form part of oil-gas separation units, and melted pipes.
"We are confident we are going back to the full production we were at before the attack (on Khurais) by the end of September," Fahad Abdulkarim, Aramco's general manager for the southern area oil operation, told reporters.
"We are working 24/7...This is a beehive."
Workmen wearing red high visibility jackets and white helmets moved through the site, a large compound the size of several football stadiums containing interconnected structures of piping and towers.
A mound of blackened debris lay on the ground. An executive said the scorched mess once covered much of the ground but now only a small mound is left.
Some workers sprayed what appeared to be water on the ground. Mobile cranes and water trucks stood near the crumpled, mangled remains of a fire-damaged stabilisation tower.
The attacks intensified a years-long struggle between Saudi Arabia and Iran, who are locked in a sometimes violent contest for influence in several flashpoints around the Middle East.
Saudi Minister of State for Foreign Affairs Adel al-Jubeir said on Thursday the attacks were an "extension of the Iranian regime's hostile and outlawed behaviour".
Iran has warned U.S. President Donald Trump against being dragged into a war in the Middle East and said it would meet any offensive action with a crushing response.