An international commission to root out corruption in Honduras denounced on Wednesday recent legislative changes that block its investigation of five lawmakers on charges of embezzling public funds.

The Organization of American States' anti-corruption mission in Honduras said that the changes would obstruct ongoing and future investigations and potentially allow imprisoned public officials to challenge their convictions, since they are retroactive.

The reforms passed last week by Honduras' Congress require all public spending to be evaluated by the country's court of auditors for a period of three years, said Juan Jimenez, the mission's leader. During that time, no civil or criminal judicial action can be taken.

The law "is saying that the (federal prosecutor's office) can't investigate," said Jimenez. "That is unconstitutional."

Jimenez said the legislative changes would freeze the case brought by Honduran prosecutors and the mission in December that alleged money for public projects was routed through a nonprofit organization and then immediately funneled into the personal bank accounts of five lawmakers.

He also said that the mission's investigation actually showed strong indications of wrongdoing by 30 current and former lawmakers, including the president of Congress, and that the number of officials under investigation could reach to more than 60.

Congress said in a statement that the changes do not imply impunity, but rather "promote transparency and accountability" by tracking the movements of all resources intended for social and community projects. The body denied that federal prosecutors would be in any way constrained.

At a news conference, Jimenez called the situation a "pact of impunity" and appealed to President Juan Orlando Hernandez to intervene. He said that on the same day Congress passed the spending changes, lawmakers also approved changes to the penal code that reduce sentences for corruption convictions.

"We don't understand how it is possible to emit a rule that looks to give impunity to 30 people who know they are under investigation," Jimenez said.

The investigation of the lawmakers would be "lost" if the law stands and responsibility is passed on to a court of auditors, which has a "political makeup," he said. A hearing in the case against the five lawmakers was scheduled for later Wednesday, but Jimenez also said he feared the judge would cite the new law in not allowing it to move forward.

Asked if the mission had faced threats during its investigation, Jimenez said that someone had contracted an international firm to investigate him, which he viewed as an attempt to "kill the messenger."

Jimenez said he and other members of the mission are committed to helping Honduras battle corruption, but he had begun consulting with OAS Secretary-General Luis Almagro about what their future might hold. He said a constitutional challenge to the law was possible.

"The corrupt people probably want the mission to leave," he said.