Red Bus is putting on extra bus tours of the red zone in Christchurch on Saturday and Sunday.

The tours cost $15 and the bus does not stop on its 30 to 40 minute journey through the centre of the city devastated by the 6.3 earthquake in February 2011 in which 185 people died.

The council-owned bus company said extra tours would run at 2pm and 3pm on Saturday and Sunday to cater for demand.

Those under 15 years of age have to be accompanied by a parent, or legal guardian, and passengers are asked to remain seated during the tour.

Disaster tourism is proving to be an unexpected spin-off for the city and locals are also interested in seeing the area they have been excluded from for so long.

A pedestrian walkway in Cathedral Square opened during two weekends in March was also popular.

The Press newspaper reported that some customers on previous bus tours thought the price was too high and others were disappointed to see the unattractive Government Life building in the square was still standing.