HOUSTON, Nov 11 (Reuters) - Venezuela’s exports of petroleum coke, a sub product from oil upgrading, have been halted at its Petrosanfelix terminal since last week due to a burning load at a vessel chartered by a unit of U.S. Koch Industries, according to a source and documents seen by Reuters on Friday.

The vessel Top Trader was receiving the load from state-run PDVSA when burning petroleum coke was noticed in three of its containers, the source said.