Lyttelton Port Co, which was taken private by Christchurch City Council last year, is suing insurance broker Aon for $184 million over the handling of its policies during the 2010 and 2011 earthquakes that resulted in the South Island's biggest marine hub settling with its insurers.

The port company filed a statement of claim in the High Court in Christchurch on June 29 seeking damages plus interest and costs, saying "Aon was negligent and in breach of contract in arranging LPC's property insurance programme for the period covering June 30, 2010, to June 30, 2011," according to a contingent liability notice in Aon's group earnings filed to the US Securities and Exchange Commission.

"LPC contends that acts and omissions by Aon caused LPC to recover less than it otherwise would have from insurers for losses suffered in the 2010/2011 Canterbury Earthquakes," it said.