* Abuses were "in violation of government policy"
* Commission report to be released on Wednesday
DUBAI, Nov 21 (Reuters) - Bahrain admitted on Monday its forces had used excessive force and mistreated detainees during democracy protests, as it awaited the release of an independent report expected to be critical of the Gulf state's handling of the unrest.
"The government has carried out its own assessments and conducted its own investigations. These investigations have revealed things to praise as well as things to deplore," said a cabinet statement sent to Reuters in English.
"Regrettably, there have been instances of excessive force and mistreatment of detainees. This was in violation of government policy. Twenty prosecutions against the officers involved have been initiated," it went on.
The death of a Bahraini teenager after he was run over by police during protests last week has raised the stakes ahead of the release of a report into the government's crushing of the democracy protest movement early this year.
Sixteen-year-old Ali Yousef al-Sitrawi was killed during a protest in the Juffair district of Manama. The government said a police vehicle lost control because of oil spilt on the road deliberately by protesters, but opposition activists say police often drove straight at them.
More than 40 people have been killed in the unrest which began in February, when thousands of Bahrainis, inspired by uprisings in Egypt and Tunisia and led by the Shi'ite majority, took over Pearl Roundabout in Manama demanding reforms.
A month later Bahrain called in Saudi and UAE troops to help crush the protests and imposed martial law.
The statement said the penal code would be amended to outlaw torture and the government would set up a National Human Rights Institution.
The Sunni-led government has said the protests were fomented by Shi'ite power Iran and aimed to establish a Shi'ite Islamist republic like Iran's. Opposition parties say the ruling elite are playing on sectarian fears to avoid reform.
REPORT DUE ON WEDNESDAY
The report by the Bahrain Independent Commission of Investigation (BICI) is due to be presented to King Hamad at a formal ceremony in his palace on Wednesday. The king requested the formation of the commission, led by eminent international rights lawyers, in June.
It is already surrounded by controversy.
The Bahraini opposition and majority Shi'ites say they expect it to play down the harshness of the government crackdown and the United States Congress has linked arms sales to Bahrain on the government's response to it.
Street protests in Shi'ite districts could erupt after the release of the report, which the government has feted in official media in advance.
The cabinet statement said police had suffered over 800 casualties and accused opposition protesters of provocation.
"Our police forces have generally shown admirable restraint when faced with great provocation. Every civilian casualty is a defeat for the government. The extremists know this, and have engaged in reckless provocation," it said.
"The police have suffered 846 injuries since the beginning of the events; four deaths; innumerable threats and insults, especially to their families."
The economy of the island state has suffered during the civil unrest. Some banks and other firms have relocated business elsewhere in the Gulf.
Bahrain offered a high interest rate of 6.273 percent on an Islamic bond worth $750 million last week, with less turnout than usual from Asian consumers of debt, in a sign of investor concern about stability in Bahrain.
The government held a "national dialogue" in June which led to some promises of parliamentary reforms. But they stop short of the key opposition demand of giving the elected chamber legislative powers and power to form cabinets.
Bahrain's government is headed by the world's longest-serving prime minister, Sheikh Khalifa bin Salman, an uncle of King Hamad who has occupied the post since 1971. (Writing by Andrew Hammond, Editing by Joseph Logan)