Diesel fuel is being stolen from pipelines, causing shortages and price increases that could threaten South Africa’s food security, according to farming lobby Agri SA.

Farmers are dependent on diesel for harvesting and to transport produce, the group said in a statement Thursday.

The dairy and fresh produce supply chain is particularly vulnerable.

The alleged theft and vandalism of diesel supply lines that run from Durban to Johannesburg have resulted in diesel being transported by truck, which increases costs, according to Agri SA. The group called for an investigation of the issue.