Police want an end to intentionally lit fires at Christchurch's Bottle Lake Forest Park

Seven fires have popped up in recent weeks, with burns in recent weeks covering more than 100 square metres.

A blaze on Monday spread 20 metres over forest ground - and took four crews an hour to extinguish.

Fire and Emergency senior officer Bruce Irvine says the risk of a fire spreading and endangering life and property is increasing, as Canterbury dries out.

Investigations are continuing.