WASHINGTON — The Bush administration will use its authority to bypass more than 30 laws and regulations to finish building 670 miles of fence along the southwest U.S. border by the end of 2008, federal officials said Tuesday.

Invoking the two legal waivers, which Congress authorized, will cut through bureaucratic red tape and sidestep environmental laws that currently impede the Homeland Security Department from building 267 miles of fencing in Arizona, California, New Mexico and Texas, according to officials familiar with the plan. The officials spoke on condition of anonymity because they were not authorized to comment publicly about it.

The move is the biggest use of legal waivers since the administration started building the fence, the department said. Previously, the department has used its waiver authority for two portions of fence in Arizona and one portion in San Diego.

"Criminal activity at the border does not stop for endless debate or protracted litigation," Homeland Security Secretary Michael Chertoff said in a statement. "These waivers will enable important security projects to keep moving forward."

As of March 17, there were 309 miles of fencing in place, leaving 361 to be completed by the end of the year to meet the department's goal. Of those, 267 miles are being held up by federal, state and local laws and regulations, the officials said.

Chertoff had said using the waivers would be a last resort. The department has held more than 100 meetings with lawmakers, environmental groups and residents in an effort to work out obstacles and objections to fence construction.

The department will conduct environmental assessments when necessary. But the waivers enable the department to start building before completing the assessments. Chertoff said the department will continue to ask for input on the construction plans.

Residents and property owners along the U.S.-Mexico border have complained about the fence construction. In South Texas, land owners refused to give the government access to property along the fence route. The government has since sued more than 50 property owners in South Texas to gain access to the land.

Environmentalists have also complained about the fence because they say it puts already-endangered species such as two types of wild cats — the ocelot and the jaguarundi — in even more danger of extinction. They say the fence would prevent them from swimming across the Rio Grande to mate.

"Unwilling to consult with local communities or to follow long-standing laws, Secretary Chertoff chose to bypass stakeholders and push through this unpopular project on April Fools' Day," Sierra Club executive director Carl Pope said in a statement. "We don't think the destruction of the borderlands region is a laughing matter."

Chertoff has said the fence is good for the environment because immigrants degrade the land with trash and human waste when they sneak illegally into the country.