By Ulf Laessing

MANAMA (Reuters) – A prominent Bahraini human rights activist went on military trial on Thursday, his daughters said, after the Gulf Arab kingdom launched a crackdown on protesters.
Sunni-led Bahrain saw the worst unrest since the 1990s in the past two months when protesters, mostly from the country's Shi'ite majority, took to the streets as Arab uprisings spread across the region.

The demonstrations prompted Bahrain's king to impose martial law and invite in troops from Sunni-ruled neighbors.
Abdulhadi al-Khawaja was arrested with two sons-in-law earlier this month as part of a government crackdown enforced with checkpoints across the city and Shi'ite villages.

Hundreds of people, many of them opposition activists and politicians, have been arrested. The government says only those accused of committing crimes have been arrested and that all accusations will be investigated.
"The trial against him (Khawaja) started today but we family members were not allowed to enter the court. I don't know what charges are brought against him," his daughter Zainab al-Khawaja said.
"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 Khawaja, who on Thursday stopped a week-long hunger strike to demand the release of her family members.
Khawaja, who lived in exile for 12 years before he was allowed to return under a general amnesty several years ago, was severely beaten upon his arrest, the Bahrain Center for Human Rights said.

He had been imprisoned for political dissent in 2004 and later pardoned by the king.
A rolling crackdown has targeted Bahrainis who took part in weeks of street protests demanding more freedoms, an end to discrimination and a constitutional monarchy in the island state, which is an U.S.-ally and home to the U.S. Fifth Fleet.

The commander of the Gulf forces called in by Bahrain, Major General Mutlaq bin Salem al-Azaima, denied allegations by some Shi'ite activists that his men were oppressing the opposition or attacking Shi'ite mosques.

"We challenge anyone to prove that we entered any street or hurt a citizen or resident. The force did not interfere in bringing order or (do) what is claimed about destroying mosques," he said in comments carried by Bahraini state media.

The United States and other Western countries have expressed muted criticism but mostly kept quiet because of the strategic importance of the oil-producing Gulf region. Amnesty International said it was time for them to speak up.

"North American and European governments, so vocal recently in espousing the cause of human rights in Libya, Tunisia and Egypt, need also to speak out loudly about what is going on in Bahrain" said Malcolm Smart, Amnesty International's director for the Middle East and North Africa.

"To avoid the charge of double standards, they must be much more robust in pressing the Bahraini authorities to uphold their international human rights obligations," he said in a statement.
The Shi'ite-led uprising unnerved neighboring Sunni countries, particularly Saudi Arabia which feared protests could spread further and embolden its own Shi'ites in the Eastern Province, home to most of the country's massive oil resources.

Gulf Arab rulers have accused non-Arab Shi'ite Iran of interfering in Bahrain after it condemned the crackdown and accused Saudi Arabia of "playing with fire" in the region. Shi'ites form at least 60 percent of the Bahrain's native population of around 600,000.
(Reporting by Ulf Laessing, Edited by Jon Boyle)