TUCSON, Ariz. (AP) — Construction on "virtual fence" projects scheduled along Arizona's border with Mexico is on hold indefinitely because the Interior Department hasn't signed off on use of its lands, federal officials said Tuesday.

Interior officials have not accepted a proposed finding that towers with radar, cameras and communications equipment would have no significant impact, said Mike Friel, a spokesman for U.S. Customs and Border Protection.

Authority to waive environmental laws for border security projects was granted in 2005, but the law does not extend to virtual fence projects, Friel said.