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DUBAI, Nov 26 (Reuters) - Saudi Arabia imposed sanctions on at least 12 senior Hezbollah figures accused of responsibility for carrying out operations for the group, which it had designated a terrorist organisation in March of last year, state media reported on Thursday.

"These names were designated today and sanctions imposed on them under the terrorism crimes and financing regime," the Interior Ministry said in a statement carried by state news agency SPA.

The statement said the Interior Ministry had also imposed sanctioned on entities that were "investment arms" for what it described as Hezbollah's sinister activities outside its Lebanon homeland.

Sunni heavyweight Saudi Arabia is a leading supporter of Sunni Muslim rebels trying to topple Syrian President Bashar al-Assad, while Iran-allied Hezbollah fighters are helping to shore up his forces against groups they call terrorist.

Hezbollah has repeatedly criticised Saudi Arabia over both its military operations in Yemen and its support for rebels in Syria.

The statement said the sanctions were based on a royal decree which targeted terrorists and those who helped them, and which included the freezing of assets of any of the designated names and banned Saudi citizens from carrying out any transactions with them.

The statement listed at least 12 people, some with aliases, including one identified as Mustafa Badreddine. A man by the same name has been accused by a U.N. tribunal in the 2005 killing of former Lebanese Prime Minister Rafik al-Hariri and is being tried in absentia. It was not immediately clear however, if the Saudi designation referred to the same Badreddine. In May, Saudi Arabia designated two senior officials of the Lebanese Hezbollah group as terrorists, accusing them of involvement in spreading "chaos and instability".

Riyadh leads a coalition of Arab states in air strikes on Houthis in Yemen, as part of a campaign to restore President Abd-Rabbu Mansour Hadi to power.

(Reporting by Katie Paul; Writing by Yara Bayoumy; Editing by Alison Williams) ((Katie.Paul@thomsonreuters.com;))