Allegations of corruption in the Gold Coast City Council relating to development decisions will be formally investigated by the Crime and Corruption Commission (CCC).

The Queensland corruption watchdog referred some matters to the Department of Local Government last September, subject to the CCC's monitoring role.

An interim report from the department prompted the CCC to start its own investigation into allegations of corrupt conduct relating to decision-making by some Gold Coast City Council councillors.

In a statement on Friday afternoon, the CCC said the allegations broadly involved possible conflicts of interests relating to decisions on a range of development matters on the Gold Coast.

"It is important to note that all allegations should be treated as unsubstantiated until the investigation is finalised," the CCC statement said.

"Whilst the investigation is progressing, the CCC is unable to comment further.

"This includes not commenting on specific developments or decisions of the council that are the subject of the investigation."

Last year, the CCC concluded Operation Belcarra, an inquiry into the 2016 local government elections involving candidates in four south-east Queensland council areas, including the Gold Coast.

Belcarra found widespread non-compliance with legislative obligations relating to council elections and political donations.