It launched a petition calling for the immediate release of the detainees.
Rising debt, increased debt issuance from other GCC states, and rising U.S. interest rates had put pressure on Bahrain's financing costs since 2014, Moody's said.
Three prominent Saudi clerics have been detained in an apparent crackdown on potential opponents of the conservative kingdom's absolute rulers, amid speculation that King Salman intends to abdicate in favour of his son.
On Wednesday, activists circulated a list of other figures they believed had been detained, including several other clerics, academics, television presenters and a poet. Such a visit, if confirmed, would be unprecedented, and potentially unpopular given Saudi Arabia's long history of not having ties with Israel. Officials in Riyadh have denied such a plan exists.
Leading Saudi journalist Jamal Khashoggi expressed outrage on Twitter following the arrests saying it is unimaginable that Sheikhs Awad Al-Qarni and Salman Al-Ouda have been arrested.
Saudi human rights group AIQST reported that Sheikh Ouda was arrested on Saturday night for posting a tweet supporting of mediation to settle dispute between Saudi Arabia and Qatar.
"The government has not clearly acknowledged this week's detentions or responded to requests for comment".
But on Tuesday, state media said a group of people acting on behalf of "foreign parties against the security of the kingdom" were being held. The contract is worth $50,000 per month. Saudi Arabia, which has accused Qatar of funding terrorism, has 20 firms on retainer.
On Saturday, Riyadh had suspended all communication with Doha after Qatari media allegedly misreported the contents of the first phone call on the crisis between the two Arab states.
But the Brotherhood has gained power elsewhere in the region. In the 1990s, the Sahwa (Awakening) movement inspired by the Muslim Brotherhood demanded political reforms that would have weakened the ruling family.
The Sahwa were largely undermined by a mixture of repression and co-optation but remain active.
Qattan said the four Arab states -Saudi Arabia, the United Arab Emirates, Bahrain and Egypt - have taken the sovereign measures against Qatar because of its wrong policies in terms of supporting and financing terrorism and hosting those involved in terrorism on its territory, spreading hatred and interfering in the internal affairs of other states.