The State Services Commissioner is launching an investigation into allegations against former employers of CERA.

A report is expected by the end of the month surrounding the alleged dealings of Murray Cleverley, Gerard Gallagher and Simon Nikoloff, who allegedly used their Public Service position to advance their private business interests.

Commissioner Peter Hughes said the allegations are "very concerning", and it'd be a "serious breach of the standards of integrity expected in the public service".

He said after a preliminary investigation by the Department of the Prime Minister and Cabinet, aided by the commission, he felt a wider probe was needed.

An investigator will be appointed to carry out the investigation by the end of the week.

"New Zealanders need to be able to have trust and confidence in public servants and the public service. These allegations raise questions that cannot be left unanswered," said Mr Hughes.

Greater Christchurch Regeneration Minister Gerry Brownlee on Tuesday said the allegations were deeply disappointing.