BHP Billiton has raised offers on manganese ore to customers in China by as much as 17%, as global supply tightens and demand picks up.

Offers of siliceous chip with minimum 43% metal content are at $7.3-7.35 per mtu for March shipment, up from $6.3 per mtu in February, according to market participants in China.

Siliceous lump, with minimum 43% metal content, is $1 higher at $7.5 per mtu.