The Papua New Guinea arm of Transparency International says a march of thousands in the capital this week sends a clear message that ordinary people oppose the changes being proposed to the Ombudsman Commission.
The anti-corruption body has described the amendments as undermining the integrity of the commission but a spokesperson for the Prime Minister's office says they simply tighten the function of the watchdog.
The Attorney General has resigned after his criticism of the legislation prompted an ultimatum from the Prime Minister.
The changes have passed their second reading in parliament but Transparency International's chairperson, Peter Aitsi, says the fact that about 5,000 people marched on the House on Tuesday to present a petition with 20,000 signatures reflects the strength of feeling against them.
"The widespread concern amongst our communities was very evident in terms of the number of people who were able to take part in the petition drive and equally the number of concerned citizens who took to the streets to show their opposition to these amendments."
Transparency International's Peter Aitsi.