Saudi Arabia said on Friday it had blacklisted four companies and three Lebanese men for having links to Lebanese Shi'ite Muslim militant group Hezbollah, a close ally of Riyadh's arch regional adversary Iran.

"The kingdom will continue its fight against the terrorist activities of the so-called Hezbollah with all available means," the Saudi Interior Ministry said in a statement carried by the state news agency SPA.

The Sunni Muslim kingdom last week suspended aid worth $3 billion to the Lebanese army over the Beirut government's failure to sign up to statements condemning attacks on Saudi diplomatic missions in Iran.

The ministry identified the four companies as Vatech SARL, Le-Hua Electronics Field Company Limited, Aero Skyone Company Limited and Labico SAL Offshore, and the men as Fadi Hussein Serhan, Adel Mohamad Cherri and Ali Zeaiter.

The statement did not elaborate. It was not known what effect Riyadh's blacklisting had on the companies' activities or whether they had business in the kingdom. Saudi officials could not immediately be reached for comment.

Last year, the US Treasury Department sanctioned the same firms and men as "Hezbollah procurement agents...responsible for providing material support to enhance the group's military and terrorist capabilities".

US-allied Saudi Arabia has also warned its citizens on Tuesday against travel to Lebanon, citing safety concerns.

In Lebanon's tangled political scene, Saudi Arabia and its Gulf allies are staunchly opposed to Hezbollah, which is part of the governing coalition and also has a heavily-armed militia.

Hezbollah is playing a crucial role in neighbouring Syria's civil war, fighting alongside President Bashar Al Assad's forces against rebels who are backed Sunni Gulf Arab states.

Relations between Shi'ite Iran and Saudi Arabia hit a new low last month when Saudi authorities executed Saudi Shi'ite cleric Nimr al-Nimr, along with three other Shi'ites and 43 members of Al Qaeda, on terrorism charges.

Protesters then assaulted Saudi diplomatic missions in Iran, leading the kingdom to cut relations with the Islamic Republic.-Reuters