Police in Horowhenua believe an increase in stock poaching could be supplying the black market for Christmas.

The number of thefts from farms has spiked from Otaki to Foxton in recent months.

The most recent was the discovery of eight sacks stuffed with sheep remains being dumped in a drain near the Piriharakeke walkway in Foxton.

A police spokesman says every week they're getting reports from farmers losing stock, with no other explanation other than rustling.

He says trends show the illegal activity typically increases this time of year, suggesting the meat is headed for the Christmas dinner table.