Protersters in Bahrain have been demanding greater political rights and freedoms [Reuters]

A prominent Bahraini human rights activist has gone on military trial, his family said on Thursday.

Abdulhadi al-Khawaja was arrested with two of his sons-in-law earlier this month as part of a government crackdown on protests the tiny Gulf island country.

Police have been arresting opposition activists at checkpoints set up across Manama, the capital, and in certain villages.

So far, hundreds of people, many of them opposition activists and politicians, have been arrested.

Khawaja was reportedly seized from his home by masked men after being beaten unconscious on April 9.

"The trial against [Khawaja] started today but we family members were not allowed to enter the court. I don't know what charges are brought against him," said Zainab al-Khawaja, the activist's daughter.

"My father called last night. He didn't sound fine. I think he has a mouth injury because he could barely speak," she said.

"He kept saying oppression is great," said Zainab, who on Thursday stopped a week-long hunger strike to demand the release of her family members.

Abdulhadi al-Khawaja had lived in exile for 12 years before he was allowed to return to the country under a general amnesty several years ago.

The Bahrain Centre for Human Rights has said that he was severely beaten upon his arrest.

He had earlier been imprisoned in 2004 for political dissent, but was later pardoned by the king.

Violent crackdown

The government has come down hard in recent weeks on Bahrainis who took part in weeks of street protests, starting February 14, demanding more freedoms and political reforms. In particular, the protesters demanded an end to discrimination against the island nation's majority Shia population and the establishment of a constitutional monarchy.

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Weeks of protests prompted the Bahraini king to impose martial law and invite troops from neighbouring countries on March 14 to help impose order.

The United States and other countries have expressed muted criticism of the government, which has used live ammunition against protesters and been accused of beating prisoners belonging to the political opposition.

The uprising in the country has unnerved neighbouring countries, particularly Saudi Arabia, which fears that protests could embolden its own Shias in the Eastern Province, home to the country's massive oil resources.

Bahrain is ruled by a Sunni monarchy, though the majority of its 600,000 population is Shia. It is also home to the US Fifth Fleet, and a key regional ally for the country.

Gulf Arab rulers have accused Iran of interfering in Bahrain, after the country condemned the Bahraini crackdown and accused Saudi Arabia of "playing with fire" in the region.

On Wednesday, a Bahraini man was put on trial in Manama for alleged links to Iran.

Ibrahim Ghuloom Abdulwahab is suspected of passing on classified military information and sensitive economic data to Iran's Revolutionary Guard over a period of nine years, starting in 2002, the state news agency reported.

Media is banned at the trial.

Source: Agencies