Saudi Arabia said on Friday it had blacklisted Hashem Safieddine, a prominent leader of the Lebanese Shi'ite Muslim group Hezbollah that is a close ally of Riyadh's arch-regional adversary Iran.

The United States Treasury Department also added Safieddine to its counter-terrorism blacklist on Friday, a day before U.S. President Donald Trump travels to Saudi Arabia.

Riyadh is the first stop on Trump's maiden international trip since taking office in January, and he is expected to conclude important security and trade agreements there with Saudi officials.

"The Saudi government today designated a leader of Hezbollah, whose name is Hashem Safieddine," Saudi state news agency SPA said. Safieddine's name was posted on the counter terrorism blacklist on the U.S. Treasury Department website.

Safieddine was working in the interest of Hezbollah in the Middle East and provided advice to launch "terrorist operations" and support the Syrian regime, SPA said.

Safieddine is president of Hezbollah's executive council, which oversees the group's social and economic activities. Hezbollah is regarded by Washington as a terrorist organization.

The group, which was formed in the 1980s to fight Israel's occupation of southern Lebanon that ended in 2000, is now fighting in Syria alongside President Bashar al-Assad's forces against rebels backed by Sunni Gulf Arab states.

Shi'ite Iran and Sunni Saudi Arabia have been locked in a harsh rivalry over power and influence in the Middle East, sometimes deploying sectarian rhetoric.

Saudi Arabia and Gulf Arab countries declared Hezbollah a terrorist organization in 2016, and said they would punish anyone who belongs to it, sympathizes with it, supports it financially or harbors any of its members.

"We will continue to designate Hezbollah's operatives, leaders and businesses, impose sanctions as a result of designation, and disrupt its radical activities," SPA said. —Reuters