A legal panel appointed by the king of Bahrain is starting its inquiry into a crackdown on protests that left more than 30 people dead earlier this year.
Hamad bin Isa al-Khalifa, who set up the fact-finding mission following diplomatic pressure, said the panel is "completely independent and consists of international experts".
The panel will be headed by Cherif Bassiouni, a US-based legal professor and UN war crimes expert, who has been nominated for the Nobel Peace Prize for his work in international criminal justice.
The fact-finding mission also includes lawyers from the UK, Iran, Kuwait and Canada, who are said to have been given access to government files and all government agencies and officials.
Al Jazeera's Charles Stratford, who reported extensively from Bahrain during the protests and subsequent crackdown, said the panel also promised secrecy for witnesses who want to testify about events that occurred in February and March.
"Obviously, there is quite a lot of scepticism about how credible in fact they are because the panel was set up by the king. This was after repeated efforts by other groups to come in and do independent investigations. They were denied access," Stratford said.
'Shia mosques demolished'
Meanwhile, a Bahraini cleric said authorities had demolished 30 Shia mosques during their five-month crackdown on dissent in the Sunni-ruled Gulf kingdom.
Seyyed Abdullah al-Ghoreifi said the mosques were destroyed as part of a government campaign against the Shia majority demanding greater freedoms and more rights.
Al-Ghoreifi spoke during a rally on Saturday on the outskirts of the capital, Manama.
The demolitions are likely to further inflame sectarian tensions in the island kingdom, the home of the US Navy's 5th Fleet.
Hundreds of protesters, activists and Shia doctors and lawyers have been detained since February when protests began. Dozens have been convicted of anti-state crimes in a special security tribunal.
Saudi Arabia has been rotating some of its troops in Bahrain, the Bahraini state news agency BNA said on Saturday, following reports more Saudi troops may have been sent to quell the unrest in the Gulf state.
Security forces from Saudi Arabia and the United Arab Emirates were sent into Bahrain in mid-March to help clear the streets of protesters.
The troops were part of a Peninsula Shield force set up by Gulf Arab states for their mutual defence.
"The Peninsula Shield forces present in Bahrain reposition certain military units ... as part of a routine operation," BNA quoted a Bahraini defence official as saying.
A witness saw no troop movements on Saturday evening on a causeway joining Saudi Arabia to neighbouring Bahrain, and a Bahraini opposition spokesman declined to comment on the report of a possible deployment of fresh forces.
On Friday, tens of thousands of people rallied in support of Bahrain's largest Shia opposition group after it pulled out of government-led national reform talks earlier this week.