FILE PHOTO: Lebanon's Prime Minister Saad al-Hariri is seen at the governmental palace in Beirut, Lebanon October 24, 2017. REUTERS/Mohamed Azakir

BEIRUT (Reuters) - Lebanon’s Prime Minister Saad al-Hariri, who sparked a political crisis on Saturday by declaring his surprise resignation in Riyadh, has traveled to the UAE, Saudi-owned media said on Tuesday.

His resignation has thrust Lebanon back onto the front line of the Middle East’s most biting rivalry, pitting a mostly Sunni bloc led by Saudi Arabia and including the UAE against Shi’ite Iran and its allies.

On Monday Saudi Arabia accused Lebanon of declaring war against it because of aggression by Iran’s Lebanese ally Hezbollah, dramatically escalating the crisis and threatening to destabilize tiny Lebanon.

The ratings agency Moody’s has said that any return in Lebanon to the political paralysis that existed before Hariri joined a national unity government last year would harm its credit rating.

The sudden nature of Hariri’s resignation has also fueled speculation in Lebanon that he was coerced into quitting and has been held against his will. Saudi Arabia has denied this.

Hariri, a political ally of Saudi Arabia, left Riyadh early on Tuesday for Abu Dhabi to meet the United Arab Emirates Crown Prince Mohammed bin Zayed al-Nahyan, the Hariri-owned Future TV and Saudi-owned al-Arabiya reported.

Saudi Arabia’s Crown Prince Mohammed bin Salman said on Tuesday that Iran’s decision to supply rockets to militias in Yemen constitutes a “direct military aggression” against the kingdom.

A rocket fired from Yemen intercepted on the outskirts of Riyadh hours after Hariri’s resignation on Saturday. On Monday, Saudi Foreign Minister Adel al-Jubeir told CNN the rocket “was an Iranian missile launched by Hezbollah”.