The Chief Ombudsman and the Privacy Commissioner will jointly investigate the Earthquake Commission's handling of official information requests.
Chief ombudsman Dame Beverley Wakem says EQC is overwhelmed by the number of official information requests it is receiving and many people aren't being given information within the 20-day limit.
Earthquake Recovery Minister Gerry Brownlee says the commission needs more resources and work is being done to increase the number of staff processing requests. He hopes three new staff will be added soon, bringing the total number to 20.
Mr Brownlee says the commission is not failing in its role; he says the huge volume of requests could not have been anticipated before the damaging earthquakes in 2010 and 2011.
But Dame Beverley says changes may be needed to help people to progress their claims and hopes to have the investigation completed by the end of July.
Labour's earthquake spokesperson Lianne Dalziel says the delays are unacceptable, citing a former Christchurch man who waited six months to get his requested information.
The Christchurch East MP says the bottleneck could have been avoided, because not all queries need to go through the official information process, and many could be answered through a quick phone call to the right person at EQC.