Malaysian police have clashed with ethnic Indian protesters in Kuala Lumpur, the country's capital.
Malaysian riot police used tear gas on the protesters
Tear gas and water cannon were used to disperse a crowd of more than 5,000 people as they rallied outside the British High Commission.
The protesters are calling for reparations from the UK for sending Indians to Malaysia as indentured labourers a century ago.
The activists also demand measures to improve the living standards of Hindus.
At least 5,000 ethnic Indian men gathered outside Kuala Lumpur's famous Petronas Towers, carrying Malaysian flags and placards.
Some demonstrators were beaten and bundled into police vans, as tear gas and water cannon were fired into the crowd, according to the Associated Press news agency.
Organisers had pledged that the demonstration would be peaceful, but Malaysian authorities nevertheless banned it, fearing that it could inflame racial tensions.
The ostensible aim of the rally was to call on the British government to pay $4 trillion (£2 trillion) in compensation to the two million ethnic Indians in Malaysia whose ancestors were taken to the country as indentured labourers in the 19th century.
But the BBC's Robin Brant in Kuala Lumpur says the real goal of the demonstrators is to highlight what they see as the unfair treatment of minority Indians in Malaysia.
Ethnic Indians - mainly Hindus - form one of Malaysia's largest minority groups.
Activists say that many Hindus live in poverty, partly because of policies granting jobs and economic advantages to the ethnic Malay Muslim majority.
"Indians are treated like third-class citizens. The community has been suffering in silence for decades," said opposition politician M. Kulasegaran.
The government has rejected claims of unfair discrimination.
In advance of the rally, three leading members of the group behind the protest - the Hindu Rights Action Force (Hindraf) - were arrested.
The three men were later charged with making seditious comments - and could face up to three years in jail if convicted.