Insurance payments following the tornado outbreak that swept across central Oklahoma in May have topped $US1 billion ($1.1 billion).

The storms included a 340kmh twister that devastated the town of Moore, killing 24 people and injuring 377.

Nearly 91,000 claims have been filed, but some are still to be resolved.

Oklahoma Insurance Commissioner John Doak says the numbers are “staggering”.

“We’ve topped $US1 billion in payments and the rebuilding is just beginning. Some survivors are still dealing with insurance and rebuilding issues.

“We can’t fix everything overnight, but we will be here for them until the last claim is paid.”