The city of Johannesburg on Monday welcomed allegations made against metro police officers in a Corruption Watch report.

"Corruption is a multi-faceted problem that impacts on many areas of society and this also impacts on the work we do," spokesman Gabu Tugwana said.

He said many measures were already in place to prevent corruption.

"Management will also thoroughly review the report and implement controls and recommendations."

On Monday, Corruption Watch executive director David Lewis released a report "The Law for Sale" on corruption within the Johannesburg metropolitan police department (JMPD).

Key findings of the report include the scale of the problem and that authorities fail to recognise it.

"[The report] criticises the JMPD for being in denial about the extent of corruption within its force. The sheer scale of the problem is massive."

He revealed that one in four Johannesburg drivers paid a bribe to traffic police in 2010.

"[The report, along with other surveys] show that one in four road users in Johannesburg has paid a bribe," he told reporters in Johannesburg, referring to a Statistics SA survey in 2010.

This amounted to about 150 000 drivers. He explained that no new survey had been done, but he believed the trend had climbed since 2010.

"Bribery is a serious crime."

The report formed part of a nationwide anti-bribery initiative, or "no more tjo-tjo" campaign, which was also announced on Monday.

The report is one of several planned by Corruption Watch to highlight graft hotspots in the country.

Lewis said JMPD statistics showed only 184 cases of corruption were reported from 2009 to 2011, in which 37 officers were found guilty and 19 were dismissed.

Corruption Watch's recommendations to the JMPD and the city were to take responsibility and address corruption. JMPD officers should at all times wear visible identification and be able to confidentially report corruption. Field integrity tests should be used to gather evidence against corrupt officers for disciplinary measures.

Lewis emphasised that bribery was not a victimless offence. Drunk drivers or motorists with defective vehicles were left to drive on the roads after paying a bribe.

"We often hear the excuse that the public is responsible for offering bribes to traffic officers, but we look up to law enforcement officers to be accountable and exemplary in their behaviour," Lewis said.

"The public would be very reluctant to offer a bribe if they knew that traffic officers always upheld the law."

Corruption Watch was started by the Congress of SA Trade Unions in January to hold public and private sector officials accountable.