Police in Malaysia have sealed off a square in Kuala Lumpur to prevent a mass rally by an opposition-backed reform group campaigning for free and fair elections. Barbed wire barricades are in place around the square.
Parliament approved a series of electoral reform measures this month, but the Bersih group says they don't address the main issue of electoral fraud.
Kuala Lumpur police chief Mohmad Salleh said his men would act against demonstrators who tried to breach the cordon around the square and surrounding streets.
Foreign Minister Anifah Aman appealed the Bersih to work to ensure that the protest passes off legally and without incident.
More than 10,000 people attended a similar rally called by Barsih last year.
The Barisan Nasional coalition has been in power since independence from Britain in 1957.
Elections are due in April 2013, but Prime Minister Najib Razak is widely expected to advance the date, possibly to June.