Lebanese President Michel Aoun says Saudi Arabia is holding Prime Minister Saad Hariri, calling the detention as an act of aggression against his country and a violation of international human rights regulations.

“Nothing justifies Hariri’s lack of return for 12 days. We therefore consider him detained. This is a violation of the Vienna agreements and human rights law,” Aoun said at a meeting with Lebanese journalists and media executives.

Aoun underlined the need for Hariri’s immediate return to Lebanon, saying, “We cannot wait a long time for Hariri’s return, we cannot stop the state’s work.”

Later on Wednesday, Hariri repeated his previous statements that he would return home. “I want to repeat and affirm that I am perfectly fine and I will return, God willing, to dear Lebanon as I promised you, you’ll see,” he wrote on Twitter.

Hariri announced his surprise resignation in Riyadh on November 4, shortly after traveling to Saudi Arabia. The televised announcement saw him reading out from a statement.

Lebanese government officials and senior sources close to Hariri believe that Riyadh forced him to step down and placed him under effective house arrest since he touched down in Saudi Arabia on November 3, a day before he announced his shock resignation.

Lebanon’s Foreign Ministry has pledged to keep up pressure on Saudi Arabia not to impede Hariri’s return, the al-Akhbar paper reported, citing sources within the ministry.

In a Sunday interview, the first since he flew to Saudi Arabia, Hariri described himself as a “free man” who intended to “return” to his home country “within days,” denying widespread speculations that he had been under house arrest.

Observers say even if he returned to Lebanon, Saudi Arabia could still hold his family “hostage.”

Hariri had taken to Twitter on Tuesday, saying he is “well” and will return to Lebanon “within days,” but that his family will stay in Saudi Arabia.

Hariri has cited several reasons, including the security situation in Lebanon, for his sudden decision. He also said that he realized a plot was being hatched against his life. Furthermore, Hariri also accused Iran and the Lebanese resistance movement, Hezbollah, of meddling in the Arab countries’ affairs; an allegation the two have strongly rejected. Hezbollah is part of the coalition government led by Hariri.

In the interview, Hariri added that he would be willing to “rescind the resignation” if intervention in regional conflicts – particularly “by Hezbollah” – stopped.