* Police detain two Western activists leading women protest
* Police use water cannon, armoured vehicles to crush march
* Two policemen injured in petrol bomb attack (Recasts with quotes, background)
By Andrew Hammond
MANAMA, Feb 17 (Reuters) - Bahraini police detained two Western activists who led a women's protest on Friday and deployed water cannon and armoured vehicles to crush a separate demonstration of around 500 people from the majority Shi'ite population following a funeral.
The Gulf Arab state has imposed a security clampdown this week in a bid to avert mass protests on the anniversary of the Feb. 14 pro-democracy uprising last year and prevent Shi'ites from reaching the Pearl Roundabout, a junction in capital Manama that became the focal point of protests.
But activists continued to stage protests in a cat-and-mouse game with police to press their demand for democratic reforms that would give Bahrain's elected parliament power to form governments. Shi'ites complain of political and economic marginalisation by the Sunni ruling Al Khalifa family, an accusation the government denies.
On Friday a group of about 150 women, led by two foreign activists, staged a protest, facing off for several minutes with lines of riot police that included a small women force. One of the protest leaders wore a T-shirt emblazoned with the words "unarmed civilian", another potester shouted: "Sunnis, Shia - brothers".
Riot police told them to break up the protest, then threw a round of stun grenades and teargas. One woman was dragged away by women riot police after she was pepper sprayed.
"These women are protesting peacefully," Medea Benjamin, an American with an observer group called Witness Bahrain, shouted as she was being dragged away. The other woman who was detained gave her name as Elaine Murthagh, an independent Irish-British activist.
At least 10 foreign activists have been deported this week.
WATER CANNON AFTER FUNERAL
Later Friday, hundreds of riot police and security forces used armoured vehicles, water cannon, teargas and stun grenades to disperse a march of more than 500 people in the Shi'ite district of Jidhafs. They were chanting against the government.
The march followed the funeral of Hussein al-Baqali, a 19-year-old who died this week from burn wounds sustained last month during tyre-burning by Shi'ites during an air show that Bahrain's government saw as a showcase event.
His family say he was unable to go to state hospitals for fear of arrest.
Sheikh Isa Qassim, seen as the most influential Shi'ite cleric in Bahrain, said in a sermon the protest movement would not give up.
"The government's methods will not affect the people's push to get their rights," he said on Friday, citing an attempt to clear the roundabout by security forces in February last year that killed four people.
"You have the machinery of destruction, but you cannot silence the voice of the people."
Qassim is close to the biggest opposition party Wefaq, which has begun contacts with a senior official in the Al Khalifa family on a possible political resolution to a crisis that has paralysed the tourism and banking hub's economy.
The violence has escalated in the last two months, with a marked rise in the use of petrol bombs against police while the number of dead, many from the effects of teargas, has risen to around 66, from 35 in June.
Police use of teargas to handle street protesters has been controversial because activists say it is used indiscriminately and the cannisters are sometimes fired directly.
On Thursday police said an improvised explosive device (IED) containing nails had been thrown at them in Sar, while in the nearby village of Bani Jamra, site of another protest, police said they had defused another IED.
Two policemen were seriously injured in a petrol bomb attack in the flashpoint town on Sitra on Wednesday.
A medic said at least 120 protesters had been wounded this week. Medics and protesters say police are using birdshot, which the police deny.
This week was the first time since a period of martial law last year that police use armoured vehicles and water cannon.
The Interior Ministry has hired two "supercops" from the United States and Britain to help improve policing after a commission of international legal experts set up to investigate last year's uprising revealed systematic torture and deaths in police custody during emergency law.
John Timoney, former chief of police in Miami, told Reuters last week that water cannon could be of some use but only in certain areas. He said teargas was preferred as the least harmful method of breaking up what police view as aimless riots.
Activists accuse the government of using excessive force.
Sayed Ibrahim, 30, said he was beaten by police after they took him inside a jeep following clashes this week in Barbar. He said they broke his arm and hand, which were both bandaged, and subjected him to sexual harassment.
"When I got in the car one of them put his hand inside my trousers," he said. "They pulled my arm back and asked if it was broken yet. They put my hand outside, then banged the door on it a few times, then hit my head with teargas cannisters." (Reporting by by Andrew Hammond; Editing by Tim Pearce and Alessandra Rizzo)