All 16,600 ComfortDelGro taxis will be installed with in-vehicle cameras over the next three months from next Monday, as an added safety and security measure, said the public transport operator on Friday.

The J002B cameras, positioned behind the rear view mirror, will be fixed in such a way that they can only record what happens outside the taxi. They cannot be adjusted to face inward, so passengers' privacy will not be compromised, said ComfortDelGro in a statement on Friday.

The device is programmed to start recording once the engine is turned on and will do so continuously for up to four hours. Its sensor is also able to activate one-minute video recordings once it detects sudden shocks to the taxi.

Equipped with a 140 deg focus lens and a 2.7-inch LCD screen, the cameras retail for $388 each but will be installed for free in the taxis. The cameras were first tested out in June this year and cabbies have given positive feedback about the cameras.