After fielding dozens of safety complaints filed in recent weeks by locked out National Grid workers, state officials on Monday announced that a natural gas pressurization incident in Woburn had spurred them to impose a moratorium on all non-emergency and non-compliance work across the utility’s service territory.

In a statement, an Executive Office of Energy and Environmental Affairs spokesman said that the Department of Public Utilities moratorium order will remain in effect pending the results of the department’s review of National Grid’s safety practices. The department is also requiring National Grid to have an inspector on location for “all work that could lead to abnormal pressurization until this review is complete,” spokesman Peter Lorenz said.

According to the company, “a National Grid gas technician inadvertently introduced excess gas into a portion of our system” while performing routine maintenance on a regulator station at Wyman Street and Hart Street in Woburn at about 11:30 a.m. Monday. “The crew quickly recognized the error and within minutes, reduced the system to normal operating pressures,” National Grid spokeswoman Christine Milligan said in a statement.

“There is no apparent damage to the system, which feeds approximately 300 homes through three miles of pipe,” Milligan said. “In addition, pressure-control devices at each property function as an extra safety measure to limit the flow of gas to safe and normal levels. As a precaution, and to confirm that there is no damage to the system, gas has been shut off to these 300 properties. Service technicians will be turning off meters and assessing the system before starting the relight process. National Grid apologizes for the inconvenience.”

During a briefing posted to Twitter by WBZ-TV, National Grid Massachusetts President Marcy Reed said workers were going door to door visiting affected homes in Woburn. She said she expected gas service to be restored to affected customers “no later than Thursday,” following assessments and testing.

Last week, the DPU reported that it had found 29 instances in which National Grid may have violated federal gas pipeline safety regulations since early July, and regulators said further investigation or other action may be necessary.

The DPU said the “information and evidence” of the alleged violations came from “concerned citizens,” though the claims overlap with a list of roughly 100 alleged violations that the unions representing locked-out National Grid gas workers have submitted to the DPU.

On Sept. 26, two weeks after gas explosions devastated Columbia Gas customers in the Merrimack Valley, the DPU said it planned to hire an evaluator to examine state natural gas infrastructure.

Lorenz said Monday that the DPU is still in the process of hiring that independent evaluator.

Since late June, about 1,250 National Grid gas workers represented by United Steelworkers Locals 12003 and 12012 have been locked out of work by National Grid amid contract negotiations. The unions have since argued that customers are less safe with National Grid’s replacement workers on the job.

“I was surprised it took this long for an incident happen to get people’s attention,” said John Buonopane, president of USW Local 12012. “But I think the state could have done this a lot sooner, and do a full investigation into how National Grid is doing during this lockout.”

National Grid said last week that its contingency workforce has completed 25,000 jobs since the lockout began on June 25.

Grade 1 gas leaks, like the one open since mid-August on Quincy Street near a Dorchester elementary school, “are considered emergency work,” Milligan said. “We respond immediately and we perform continuous action until the leak is remediated. That has not changed.”

Reporter news editor Jennifer Smith contributed to this report.