Insurers in California say claims arising from the bushfires which swept through the state a few weeks ago are now expected to be the costliest in US history. Standard & Poor’s says the loss estimates now total $3.4 billion.

But it says the claims won’t affect the ratings of the insurers involved. Most of them are national companies well insulated against risks from a single state.

The wildfires destroyed about 4000 homes, killed 20 people and cost the state of California about $300 million to extinguish.