mining at a snail's pace

New Zealand's biggest coal exporter says endangered snails have disrupted mining operations, costing the company about $20 million in lost production.

Solid Energy's new mine near Stockton, on the west coast of New Zealand's South Island, ran into trouble with environmentalists because it is also the native habitat of the giant land snail - Powelliphanta augustus.

Campaigners picketed the remote site until the company agreed to relocate about 1,000 of the rare snails.

Chief executive Don Elder now says it turns out there are five times as many snails as originally thought, so production will stop in May and June while the collection is completed.

As a result, up to five export shipments will be lost, costing the company more than $20 million.