The United Kingdom, France and Germany said late Monday in a United Nations session that "it is clear" Iran is responsible for the recent attack on Saudi Arabian oil facilities.

U.S. President Donald Trump also said that he will discuss Iran in his upcoming U.N. speech on Tuesday, adding "we have a lot of pressure on Iran."

Britain had previously concluded that Iran was responsible for attacks on oil facilities in Saudi Arabia, as Prime Minister Boris Johnson said the previous day. He said the U.K. would consider taking part in a U.S.-led military effort to bolster the Gulf kingdom's defenses.

A U.K. official told The Associated Press that a claim of responsibility for the attacks by Iran-allied Houthi rebels in Yemen was "implausible." He said remnants of Iran-made cruise missiles were found at the attack site, and "the sophistication points very, very firmly to Iranian involvement." He spoke on the condition of anonymity to discuss intelligence findings.

The official did not say whether Britain believed the attack was launched from Iranian soil.

Iran denies responsibility and has warned any retaliatory attack targeting it will result in an "all-out war."