BOSTON (AP) — State regulators have ordered a halt to all non-emergency natural gas work by Columbia Gas, the utility involved in last month's explosions and fires in three Massachusetts communities.

The moratorium imposed Friday by the Department of Public Utilities covers all parts of the state serviced by the company. While officials say the order won't interrupt the ongoing restoration of natural gas to customers in Lawrence, Andover and North Andover, any other work must be approved in advance by the agency.

A spokesman for the agency says the directive follows a preliminary report issued Thursday by the National Transportation Safety Board on the Sept. 13 disaster.

The report found that over-pressurization during a pipeline replacement project led to the explosions and fires that killed one person and injured some 25 others.