Iran’s officials and clerics stepped up their criticism of Saudi Arabia on Friday, accusing the Kingdom of the “arrest” of Lebanon’s Prime Minister Saad al-Hariri.

Hariri announced his resignation last weekend from Riyadh, but has not been seen since then. The absence has fueled speculation that authorities have put Hariri, a Saudi citizen, under house arrest. On Thursday, Lebanese officials expressed concern that he may have been detained and called for his return to Beirut.

A possible explanation for Hariri’s enforced stay in Saudi Arabia is that he is being questioned in connection with a crackdown by Crown Prince Mohammad bin Salman. The rising power in the Kingdom, the Crown Prince has declared a campaign against “corruption” with the arrest of more than 200 people, including other princes and some of Saudi Arabia’s richest men.

Hariri’s father Rafik Hariri, a former Lebanese Prime Minister killed in 2005 by a car bomb, built up his business interests — and helped revive Beirut after the Lebanese Civil War — with connections with Saudi business interests, including some of those who have been detained in the past week.

But Hariri’s departure from power has thrown Lebanon’s coalition government, formed in October 2016 after a two-year stalemate and including Iran’s ally Hezbollah, into disarray and fueled the possibility of conflict inside the country. Earlier this week, Saudi Arabia has accused both Iran and Hezbollah of “acts of war”.

Tehran Friday Prayer leader Ahmad Khatami said yesterday that the Saudis invited Hariri to Riyadh “and then arrested him”, as worshippers chanted “Death to America, Israel, England, and al-Saud”.

Foreign Minister Mohammad Javad Zarif framed his denunciation in more measured language, while linking the latest events to Saudi Arabia’s military intervention in Yemen and break with neighbor Qatar:

In Lebanon, Hezbollah leader Hassan Nasrallah, in a televised speech, accused Riyadh of “blunt, unprecedented interference”:

All of a sudden, out of nowhere, Saudi Arabia called the prime minister on urgent matter without his aide or advisers, and [he] was forced to tender his resignation, and to read the resignation statement written by them.

We declare that the prime minister of Lebanon has not resigned. Saad Hariri is our political opponent, but he is also our prime minister.