The leader of the Hezbollah militant group in Lebanon on Friday accused Saudi Arabia of declaring war on his country, a week after the country’s Prime Minister Saad al-Hariri announced his resignation in Riyadh, the BBC reported.

Hassan Nasrallah said he was sure that Hariri was forced to resign as part of what he called Saudi Arabia’s policy of inciting sectarian tensions in Lebanon. He accused Riyadh of “blunt, unprecedented interference”, Al Jazeera reported.

“We declare that the prime minister of Lebanon has not resigned,” Nasrallah said in a televised speech. “Saad Hariri is our political opponent, but he is also our prime minister.”

Nasrallah urged his followers not to be anxious or frightened, and said that leaders across the political spectrum were staying in contact and were trying to maintain calm, the Financial Times reported.

Lebanese President Michel Aoun on Friday told Saudi Arabia’s envoy to the country, Walid al-Bukhari, that the circumstance in which Hariri resigned were unacceptable and that he must return to the country, Reuters reported.