Last week Bangkok hosted the third meeting of the United Nations' Intergovernmental Panel of Climate Change, which released a landmark report on measures governments need to take to tackle global warming.
Non-essential lights 
Bangkok's neon-lit nightspots will be among
those expected to go dark [EPA]
City authorities have stressed that only non-essential lights need to be turned off and extra police will be deployed on the streets.
''These include billboard lights, decorative lighting at department stores and in shopfront windows, and some lights in households," Apirak said.
He said the event was designed to drive home the message about cutting energy consumption.
However, the Bangkok Post newspaper said some city residents have raised concerns over the timing of the event, in a city which has been hit by a series of small bomb blasts in recent months.
The latest blast on Saturday in a phone box close to a royal palace injured one passer-by.
The newspaper said part of the authorities' reaction to the bombings has been to promise more lights in poorly-lit areas.
The lights out campaign follows a similar event in Sydney in March, when Australia's largest city went dark for an hour, turning off the lights in homes and on such iconic landmarks as the Sydney Opera House and the harbour bridge.