Slovenia scored 57 points out of 100 and the poor ranking is a clear warning for the government and politicians that problems will not be solved by pointing the finger at others, Integriteta said.
The organisation has joined the appeal of the recently resigned heads of the Corruption Prevention Commission for change. However, there is still no political will for systemic changes, it said.
The corruption perception index in the public sector is based on corruption perception of business representatives and analysts.
The results show that the countries that promote transparency and accountability are more successful in corruption prevention, Integriteta said. While in Slovenia "some still seem to be afraid of public access".
Integriteta president Simona Habič was very critical, saying that the results reflect in the parliament's passing of laws, which violate the Constitution, under the influence of lobbyists.
The legislation tailored to lobbies encroaches on the people's social and labour rights, as well as rights to pension, healthcare, a decent life and the right to live in a rule of law, the organisation said.
"But citizens continue to vote for the same people. Even though they are not happy with them, they turn a blind eye and forget what they had done. We must say no to this," said Habič.
Public spending must be transparent and all deals accessible to the public because independent institutions pointed to a number of irregularities, Habič said.
She moreover said that jeopardising oversight bodies and calls for their abolishment went against Slovenia's international obligations and led to politicising of the institutions.