The downstream energy insurance sector suffered its worst loss in nearly a decade last year, according a market review from Willis Towers Watson.

The sector covers the refining of crude oil and natural gas, and their marketing and distribution.

The sector lost more than $US5.5 billion ($7.15 billion) last year, and few sector insurers recorded a profitable year.

The upstream energy insurance sector – covering exploration and production – lost only $US1.3 billion ($1.7 billion), in one of its most benign loss years on record.

There remains availability of capital and increasing capacity in the energy insurance market, ensuring its stability, Willis Towers Watson says.

Downstream energy insurance capacity has increased to $US6.8 billion ($8.8 billion), while the upstream energy sector’s has risen to $US7.95 billion ($10 billion).