Groundbreaking will begin next week in southern Arizona for the virtual fence project's first permanent detection towers, a spokeswoman in Washington said Friday.

Contractors preparing sites for the towers "will start moving earth next week," Customs and Border Protection spokeswoman Jenny Burke said.

The towers will hold sensors, cameras and communications equipment designed to detect illegal immigrants and drug smugglers and to enhance the ability of Border Patrol agents to intercept and apprehend them.

The towers are to be built first in Arizona, the busiest corridor for illegal entries along the Mexican frontier over the past decade. Plans call for also placing such towers along most of the 2,000-mile Mexican border, in New Mexico, California and almost all of Texas within five years.

But within the next few weeks, Burke said, officials with the Secure Border Initiative have to assure that problems that came up with various components during systems testing have been resolved.

"The Department of Homeland Security has to give approval before we hang sensors on the towers," she said.

"There were some issues that cropped up during systems testing qualifications. SBI believes that they have been fixed," and will seek to provide assurance of that during the next couple of weeks, Burke said.

The first permanent towers will encompass a total of 53 miles of the Arizona border in two chunks southwest of Tucson. One will replace a prototype temporary virtual fence near Sasabe.