BEIRUT — The political party of Lebanese Prime Minister Saad Hariri, who resigned under mysterious circumstances five days ago while in Saudi Arabia, demanded on Thursday that he return from the kingdom immediately in a statement that seemed to imply he was being held against his will.
Saudi Arabia meanwhile ordered all of its citizens to ‘‘immediately’’ depart Lebanon amid heightened tensions with Hezbollah and the militant group’s patron, Iran. A brief statement carried by the state-run Saudi Press Agency also warned Saudis against travel to the country.
Saudi Arabia’s Foreign Minister Adel al-Jubeir warned earlier this week that his government would ‘‘deal with’’ Lebanon as a hostile state as long as Hezbollah was in the government. He said Hezbollah’s participation in government is an ‘‘act of war’’ against Saudi Arabia.
Hariri surprised the country by announcing his resignation Saturday in a pre-recorded message during a visit to Saudi Arabia. Even close associates in his party, the Saudi-aligned Future Movement, have said they don’t know why he resigned.
On Thursday, the party called on him to return.
‘‘The return of the Lebanese prime minister, the national leader, Saad Hariri, and the head of the Future Movement, is necessary to restore the dignity and respect to Lebanon at home and abroad,’’ it said in a statement read by former prime minister Fouad Saniora, who heads its parliamentary bloc.
Hariri is known to have left the kingdom once since announcing his resignation, on a brief trip to the United Arab Emirates, a close Saudi ally.
Hariri’s office released a statement Thursday saying he has met with the French ambassador to Saudi Arabia and the European Union envoy to the kingdom, as well as US and British diplomats.
His resignation remains shrouded in mystery. In his televised statement, he said Lebanon had been taken hostage by Hezbollah — even though he formed a coalition government with the group, which has a substantial representation in Parliament, less than one year ago.
Hezbollah’s leader and one of Lebanon’s most powerful figures, Hassan Nasrallah, has speculated openly that Hariri was being held against his will in the kingdom and even said that it appeared as if Saudi Arabia forced the resignation.
The Future Movement statement suggested the party was moving toward the same conclusion.
French President Emmanuel Macron, who is visiting the UAE, declined to discuss Hariri’s resignation, saying only that he hopes Lebanon will have a new government soon. He was set to travel to Saudi Arabia later Thursday to discuss the situation in Lebanon and other issues.
‘‘We’ve had some contacts but there’s no reason to say anything official about this,’’ Macron said of Hariri.
Hariri’s father, former prime minister Rafik Hariri, was killed in a massive car bombing in Beirut in 2005. The bombing was widely blamed on Hezbollah, which denied responsibility.
After he was ousted as prime minister in 2011, Saad Hariri, who has Lebanese and Saudi citizenship, split his time between France and Saudi Arabia until he returned to Lebanon in 2014.
Hezbollah has called on Saudi Arabia to stay out of Lebanese affairs, saying Hariri’s resignation from Riyadh ‘‘raised many questions.’’
Hezbollah has been represented in Lebanon’s Parliament since 1992. Its armed wing has an arsenal that rivals that of Lebanon’s army, and its fighters are aligned against Saudi-backed rebels in the civil war in neighboring Syria.