Indonesian to English Bus/Financial Law: Contract(s) contract for perfomance of mining works

In the following sentence, what is a good translation of 'pelanggaran fatal'?

"Pemilik atas pertimbangannya sendiri berhak memerintahkan kepada Kontraktor untuk mengeluarkan tenaga kerja Kontraktor dari Lokasi dan Areal Penambangan, atau dari kegiatan yang berkaitan dengan Pekerjaan. Apabila tenaga kerja tersebut terbukti melakukan pelanggaran fatal dan sebelumnya telah mendapat surat peringatan." (I suspect this should be one sentence, not two, but that's how it appears in the source document.)

The phrase 'pelanggaran fatal' appears many times in documents referring to human rights abuses and is, literally, a 'fatal offence' or 'fatal violation', i.e., causing death. However, I feel that the contract language cited conveys a different intent, i.e., that a worker has previously been warned and then does something wrong with very serious consequences. I doubt a worker would be ejected from a worksite only if he's killed someone and been given a warning. It must mean something like a 'fatal error', which actually applies only to computer errors. Maybe it means 'pelanggaran berat' = 'serious violation'. What do you think?