MEXICO CITY/HOUSTON, Oct 12 (Reuters) - Pemex's Deer

Park oil refinery near Houston discharged 43,500 pounds of

highly toxic hydrogen sulfide gas over more than seven hours in

a deadly incident earlier this week, according to the Mexican

state-owned company's disclosure to a Texas regulator.

The accident on Thursday killed two contract workers

while injuring 35 others during work on a unit at the refinery.

According to Pemex's initial report to the Texas

Commission on Environmental Quality, the Oct. 10 leak continued

for 7 hours and 40 minutes. Over the course of the incident, the

hydrogen sulfide discharge exceeded more than 800 times the

hourly emission limit for the dangerous gas of 6.89 pounds per

hour.

The data from the Texas regulator is dated Oct. 11.

The refinery, which features a crude processing capacity

of 312,500 barrels per day, will operate this weekend at a "low

level" as Pemex investigates the cause of the leak, the company

said late on Friday in a statement.

Houston-based Buzbee Law Firm said it had been retained by

"several families impacted by this horrific incident."

Pemex management has operated the facility for nearly three

years.

Work was underway on a sulfur recovery unit at the time of

the fatal discharge, according to people familiar with the

matter.

The Deer Park refinery is a major motor fuels supplier to

Mexico, where the government has sought to reduce reliance on

gasoline and diesel imports from non-Pemex refiners in a push to

be more energy self-sufficient.

Pemex's newly-appointed CEO Victor Rodriguez told reporters

on Friday morning that thirteen workers remained hospitalized

after being exposed to the leak, while Mexico's energy minister

said at the same briefing that she expected the facility to be

back to normal operations later on Friday.

But the company walked back that expectation with its latest

statement.

"The refinery continues to operate in stable conditions at a

low level, a level that will be kept in place during the weekend

as long as it's possible to have access to the areas to carry

out the corresponding inspections," the company said in its

Friday night statement.

Rodriguez, who took over earlier this month, noted on Friday

that three or four units had been shut at the refinery following

the leak.

The U.S. Chemical Safety and Hazard Investigation Board

(CSB), which investigates industrial accidents and makes

recommendations to prevent future incidents, has also begun a

probe of what it described as a "very serious incident."

CSB said late on Friday that its investigators should arrive

at the refinery on Saturday.

Deer Park for decades was operated by oil major Shell, but

Pemex took full ownership of the refinery in early 2022,

acquiring Shell's 50% stake in what had been a long-standing

joint venture.

In 2021, Shell disclosed that it sold its interest in Deer

Park to Pemex for some $596 million.

Pemex's domestic refineries have for years suffered major

accidents, including explosions and fires, that have caused

deaths in Mexico.