OCP detected a leak in Napo province in central Ecuador and immediately activated its emergency response plan which led to the shutdown, the company said in a statement.
OCP is "actively working" to control the situation, it said, without specifying the size of the leak.
The 485-kilometer (301.37-mile) pipeline, the country's second largest, can transport about 450,000 barrels per day, though it has been operating below capacity.
OCP's contract to operate the pipeline had been due to expire in January. The company said then it was in talks with the government to transfer the pipeline to state control.
The pipeline construction required $1.4 billion in private funding, OCP data showed.
