ExxonMobil announced Friday evening that the long-awaited restart of its Torrance refinery, scheduled for 7 p.m. Saturday to 7 a.m. Sunday, would be postponed two days for “operational” reasons, authorities said.

“ExxonMobil told us they were not ready,” said Sam Atwood, spokesman for the South Coast Air Quality Management District, which made the announcement on its website shortly before 6 p.m. “They were concerned they would not have adequate time to complete the process by 7 a.m. this Sunday. They didn’t say why.”

The restart is now set for between 7 p.m. Monday and 7 a.m. Tuesday.

Company officials did not immediately respond to a request for comment.

Several South Bay residents had criticized the company’s decision to restart the refinery for the first time in 15 months on Mother’s Day.

Torrance resident Teresa Kalmar, who lives three blocks from the refinery, had planned to move a Mother’s Day brunch on her patio with about 20 guests — including her 90-year-old mother and a 7-week-old grandson — to Orange County.

The plant is expected to spew excess pollutants for about six hours in violation of emission regulations after the restart is initiated, although authorities have said they are not expected to “exceed health-based thresholds.”

“To choose this date when guests are coming to visit, out-of-town visitors, children are coming to visit their grandmothers, I think it is a slap in the face to our mothers group that fought so hard for our safety,” Kalmar said.

The South Coast Air Quality Management District Hearing Board last month agreed to allow the company to restart the refinery without pollution-control devices, which present a greater risk of a fire or explosion, such as the one in February 2015, that crippled the plant’s ability to produce gasoline.

It was in the company’s electrostatic precipitator — the refinery’s main pollution-control device — where hydrocarbons ignited and caused an explosion that rocked the region with a force equivalent to a 1.7-magnitude earthquake.

Four workers narrowly escaped injury, industrial debris was showered over some South Bay neighborhoods and pump prices soared for months, costing California motorists $2.4 billion through higher pump prices in the following six months, according to a RAND study. Federal officials later said the blast almost caused a catastrophic release of highly toxic hydrofluoric acid that could have killed or injured thousands.

The state fined the company more than $500,000, with the AQMD adding in another $5 million fine — in part for the pollution the company will cause when the refinery resumes operations.

It was two moms from the grass-roots group South Bay FLARE — Families Lobbying Against Refinery Emissions, which was founded after the explosion — who had hurriedly persuaded regulators as the AQMD meeting drew to a close to impose conditions on the restart.

That included a 48-hour notice to the community, door-hangers delivered to homes and businesses within one mile of the refinery and an order that the refinery restart between 7 p.m. and 7 a.m. to reduce public exposure to pollution.

FLARE members, many of them young mothers, had not expected the company to choose Mother’s Day, however.

“It’s a fitting insult to the injury,” said Jamie Court, president of Santa Monica-based nonprofit Consumer Watchdog, before adding sarcastically, “It’s a beautiful Mother’s Day gift to the community.”

“Hopping mad” Redondo Beach retiree Melanie Cohen was so fed up she fled town earlier this week and had planned not to return until Tuesday.

“I wanted to make sure I was nowhere near the South Bay when this dangerously defective refinery is going to go online again,” she said Friday from a Ventura hotel.

ExxonMobil must demonstrate to would-be refinery buyer PBF Energy that the refinery can operate safely when operations resume so that the previously announced $537.5 million sale of the refinery can close.

Meanwhile, Torrance Fire Chief Martin Serna said Friday that the department did not plan to increase staffing levels in response to the restart.

And the AQMD has installed two air monitors near the refinery to check on emission levels during the initial six hours of the startup, Atwood said. The agency also will require ExxonMobil to redeliver notices of the restart schedule to about 11,000 households and businesses within a one-mile radius of the refinery.

“We want to ensure that residents have adequate and proper notice of the rescheduled refinery restart,” said Wayne Nastri, acting executive officer for AQMD. “Meanwhile we will be monitoring air quality before, during and after the startup to assess any potential air pollution impacts in the community.”

Residents can report air quality issues to the AQMD by calling its toll-free complaint line, 800-CUT-SMOG.