Malaysian police on Friday were putting up road blocks and spot checking vehicles entering Kuala Lumpur ahead of a planned lockdown to block a protest for electoral reform, according to dpa. Activists have said they plan to hold the demonstration at the city\'s Merdeka Stadium despite the authorities declaring it illegal and police warning that participants would be detained. Any gathering of more than five people requires authorization in Malaysia. Discussions with the authorities over moving the demonstration off the streets to an agreed venue broke down this week. Acting city police chief Amar Singh said three major bus terminals would also be shut down, and bus routes diverted around Kuala Lumpur for 22 hours starting midnight (1600 GMT) on Friday. Around 250 people, including an opposition lawmaker, have been detained for allegedly promoting the protest by distributing leaflets or wearing the rally\'s distinctive yellow T-shirts. Trucks of riot control and military personnel were seen throughout the capital Friday, creating a tension unusual in Malaysia where large-scale anti-government protests are rare. Police have already warned they will make mass arrests and use the full force of the law against activists. Organizers of the demonstration are demanding more transparency in election laws, saying current regulations favour the government. Activists have maintained that they are exercising their right to peaceful assembly and have refused to back down, even challenging the home minister\'s ban on the rally in court. Prime Minister Najib Razak has defended the authorities\' harsh actions over the past two weeks, saying the massive protest would create chaos and disrupt businesses. Activists and rights groups have described the official crackdown as a \"low point for human rights.\"