As this practice is going on unabated, the government and private owners of buildings have to spend a lot on cleaning, whitewashing and colouring the walls.

Small business firms like coaching centers, beauty parlours and clinics opt for graffiti, posters and banners as these are the cheapest means of advertisement.

Dhaka City Corporation (DCC) sources said people engaged in such activities can be punished for damaging public or private property as per existing law.

"Small firms are inclining towards graffiti and banners to get maximum exposure for their products or services at the lowest cost," said a resident of Dhanmondi.

The business firms hire signboard painters who write the graffiti after midnight. Street urchins help them in finishing the job as quickly as possible.

Political activists or aspirants of any election also use the walls for their campaign but they never ask for permission of the building owners.

Most private house and other establishment owners are now going for whitewashing their walls instead of using distemper or plastic emulsion paints as whitewashing costs much less than distempering the walls.

"I had no other choice but to whitewash my walls as I had distempered these around three times earlier but within a week or two, I found new graffiti on them," said Kabir Ahmed, a house owner residing of Kalabagan.

The owners spend around Tk 1,500 to Tk 2,000 to paint a 10X20 feet wall with plastic emulsion while whitewashing costs Tk 700 to Tk 900. Owners however said whitewashed walls are damped easily during the rainy season.

Matters are worse for public property like government office buildings, schools and colleges, as these are usually re-painted once in a year.

When contacted, the manager of an advertising firm said they take permission from the owners before using their walls for graffiti.

But the principal of Law College at Kalabagan said nobody ever came to ask for permission for putting graffiti on the college walls.

Senior officials of the Conservancy Department of DCC said they have started a drive recently to stop this practice. They will contact the advertisers and ask them to repaint the walls back to its original form.

"We will be bound to take lawful measures against them if they do not comply to this direction," said a DCC official.