A Government Accountability Office (GAO) report slated to be released today says that new detectors for scanning cargo for radiological and nuclear material perform no better than the current detectors,according to the Associated Press.

The Department of Homeland Security (DHS) has said the new machines it is developing can distinguish between kitty litter and dangerous radioactive material and produce fewer false alarms than the current ones.

The new one are also better at detecting lightly shielded material. But the machines perform at about the same level when detecting radiological and nuclear materials hidden in a lead box or casing, the most likely way a terrorist would try to sneak the materials into this country, the Government Accountability Office said in a report to be released Monday.

The AP reports that the GAO report wonders whether the new detectors are worth the cost. One new detector costs $822,000 while the older detectors that perform as well as the new detectors cost $308,000.

DHS told the AP it would not comment because the report had not been released.

This isn't the first time the GAO has reviewed the new detectors unfavorably