Two Saudi oil tankers were targeted on Sunday in “a sabotage attack” off the coast of Fujairah, part of the United Arab Emirates, Saudi Arabian Energy Minister Khalid al-Falih said on Monday.

The attack did not lead to any casualties or an oil spill but caused significant damage to the structures of the two vessels, he added, according to Reuters.

On Sunday, the UAE foreign ministry said four commercial vessels were targeted by “sabotage operations” near the territorial waters of the United Arab Emirates without causing casualties.

Iran, embroiled in an escalating war of words with the United States over sanctions and the U.S. military’s presence in the region, moved on Monday to distance itself.

The foreign ministry called the incidents “worrisome and dreadful” and asked for an investigation into the matter. A senior Iranian lawmaker said “saboteurs from a third country” could be behind it, after saying on Sunday that the incident showed that the security of Gulf states is fragile.