WASHINGTON (Reuters) - The Department of Homeland Security proposed new security measures on Tuesday to monitor sales of ammonium nitrate, a chemical compound widely used in fertilizer but also the key ingredient in some bombs.
Under pressure to finalize the new rules, the department proposed requiring buyers and sellers to register and be verified before completing transactions involving the sale of 25 pounds (11.3 kgs) or more of the chemical.
"In today's ever-evolving threat environment, we must continually reinforce the security of substances, such as ammonium nitrate, which can be used for legitimate purposes or exploited by terrorists," DHS Secretary Janet Napolitano said in a statement.
Last month a car bomb that exploded outside the Norwegian prime minister's office, killing eight, reportedly used an ammonium nitrate-based compound.
It was also used more than 15 years ago in the 1995 bombing of a federal building in Oklahoma City that killed 168 people.
Authorities allege that a Marine reservist charged in June with shooting at military sites around Washington, D.C., had small bags of the chemical with him when he was arrested.
Homeland Security proposed requiring sellers to keep records of transactions and thefts of the chemical would have to be reported quickly to authorities.
But the U.S. government's efforts to control the substance has a long way to go. Homeland Security is seeking public comment for four months and will have to take those into account to finalize the rule, which could take more time.
The proposed U.S. reporting requirements would not only affect farmers and agricultural retailers, but also landscaping companies, construction and mining companies, laboratories and even golf courses that use it in fertilizer.
"With any of these initiatives, the key question is what is the threat and what's the vulnerability," said Michael Balboni, a senior fellow at the George Washington University's Homeland Security Policy Institute. "It's not so much the amount as who's purchasing it."
The Homeland Security department estimated there may be as many as 106,000 buyers of the chemical. Congress first ordered the department to develop the regulations in 2007 and it issued a preliminary proposal in 2008.
"I would hope that there would be a way to expedite the regulatory considerations when it affects security," said Balboni, who helped develop regulations on ammonium nitrate in New York State. Most states now have rules for sales of the chemical.
(Editing by Christopher Wilson)