Rio de Janeiro's preparations for the World Cup and Olympics have so far mostly focussed on efforts to sweep crime off the streets, but now the city has opened up a new front in its clean-up campaign: a draconian clampdown on litterbugs.

As well as an escalating scale of fines ranging from £30 for pet litter to almost £1,000 for fly-tipping, the authorities say they will also give a "dirty name" to citizens who are caught dropping rubbish, and who fail to pay the penalty. This will be noted on their identification documents, and will appear whenever they apply for credit cards or loans.

The lixo zero (zero waste) law was supposed to have been introduced in July, but was postponed because of the recent papal visit and mass demonstrations against public bus fare increases, which showed widespread resistance to new levies in the city. Rio's mayor, Eduardo Paes, said he also wanted more time to raise public awareness of the issue.

At the start of the campaign on Tuesday, sanitation workers were accompanied by armed police officers.

Vinicius Roriz, president of Comlurb, Rio's waste collection operator, said the primary focus would be on the most crowded areas of the city, but the programme would later be expanded to the favelas on the periphery.

"We won't fine on the spot, but we will take people's CPF numbers," he said, referring to the most widely used identification document. "If they don't pay later, we will mark it on their CPF, which would give them a dirty name."

Critics say the penalties are disproportionately high, and that the infrastructure is lacking to allow citizens to dispose of rubbish easily.

The fine for dropping a can is more than a fifth of the minimum monthly salary of 763.14 reais (£200).

"The fee is really expensive. I wouldn't have the money to pay," said Dimmy Trinidade, an architecture student as the Federal University of Rio de Janeiro. "I think that the prefecture should have more bins."

Comlurb says it will open more municipal dump sites and study whether to install new bins made of coconut fibre. It is hoped these will be less susceptible to theft than the plastic models, which are often stolen and sold to private recyclers.

To educate the public about the scale of the littering problem, Rio halted normal rubbish collections earlier this month on a stretch of beach in Ipanema, to show how much rubbish accumulates on the sand in a single weekend. Photographs of the stinking piles of rubbish were published in local newspapers.

"I'm 100% in favour of this programme," said Pedro Gomes, an engineer who works in the Centro district.

"Brazilians are pigs, they throw rubbish on the floor all the time. It's really unacceptable. What's worse is that the upper classes, even 'educated' people, do this too."

But the city itself also has some dirty habits to clean up: Comlurb seperates barely more than 0.25% of Rio's urban waste, and much of the municipal sewage is still discharged untreated into the ocean.

Additional reporting by Anna Kaiser