Embattled PG&E Corp. reportedly delayed safety work on a century-old high-voltage transmission line that is the main suspect behind the deadliest wildfire in California's history.

The electric and gas company told regulators in 2013 it intended to replace much of the infrastructure, including towers and wires on the so-called Caribou-Palermo line, the Wall Street Journal reported Wednesday. However, the company resubmitted that plan in 2014, 2015 and 2016, postponing the proposed fixes each year.

Most recently, the company planned to begin work on June 2018 and finish later in the year, though such work has not begun, the Journal added.

Shares of PG&E, which had been up prior to the report, last traded down 3.8 percent. The company did not have a comment immediately available when CNBC contacted it for a response. The stock price has plunged since the company announced it plans to pursue Chapter 11 bankruptcy.

PG&E faces at least $30 billion in potential liability costs stemming from wildfires in 2017 and 2018, many allegedly started by the company's equipment, that have led state officials to doubt the safety of the company's electric distribution system.

Investigators have already determined PG&E's equipment liable in at least 17 major wildfires in 2017. State investigators are still examining whether the company's equipment was partly responsible for November's Camp Fire, which killed at least 86 people and destroyed about 14,000 homes, making it the state's deadliest fire.

This story is developing. Please check back for updates. Click here for the original Wall Street Journal report.