Suncorp has warned of an unexpected jump in the cost of settling older car and home insurance claims, blaming more expensive motor repairs, a spike in water damage to properties and a freak jump in house fires for a higher damages bill.

In a trading update on Monday, the Brisbane-based group – whose brands including AAMI and Apia – also confirmed that wild weather damage since late November had largely eroded the benefits of benign weather earlier this financial year.