America's transport watchdog vowed not to slow global trade by piling security measures onto the aviation industry in response to terror threats as air lobby group IATA warned against rash action.

"Security cannot bring business to a standstill," said John Pistole, who was made head of the U.S. Transportation Security Administration (TSA) earlier this year, at an aviation security conference.

"We must strike that balance (between security and business). The U.S. government understands this well."

Two packages containing bombs -- both sent from Yemen and addressed to synagogues in Chicago -- were intercepted in Britain and Dubai on Friday.

One of the packages was found on a United Parcel Servicecargo plane at East Midlands Airport in Britain. The other was discovered in a computer printer cartridge in a parcel at a FedEx facility in Dubai.

Air cargo accounts for just over a third of global trade by value, and airline industry body International Air Transport Association (IATA) warned that knee-jerk regulatory reactions by governments could impede the flow of goods.

"We have seen many cases where (solutions) have unintended consequences," said Giovanni Bisignani, Director General of IATA, at the conference. The bomb plot may speed up calls for wider use of sophisticated imaging technology that detect explosives but freight firms are wary of the costs.

Slow-Down
Also, there is concern that heightened security will slow trade flows or make delivery times less predictable.

"If security checks take two days sometimes and sometimes half-a-day, the variability is the problem," said Joern-Henrik Thun, professor of Operations Strategy at the Frankfurt School of Finance and Management.

Companies that now fly in parts from faraway places -- such as China -- may purchase goods from countries that are less far away or are seen as less risky politically, he said.

"We will probably have to adjust ourselves to longer throughput times where more documentation is required," said German engineering industry group VDMA's President Thomas Lindner at a news briefing on Tuesday.

According to IATA, airlines transported 26 million tonnes of international cargo last year, of which more than 40 percent was in the cargo hold of passenger planes.

Analysts have said airlines could face pressure following last week's security scare to put less cargo on passenger planes or improve blast protection.

"We are overreacting sometimes by putting passengers through excessive inconvenience," Qatar Airways' Chief Executive Akbar Al Baker sai.

IATA's Bisignani in an interview with Reuters Insider dismissed concerns the latest security scare could have an impact on demand for air travel or cargo services.

"We are still forecasting a positive result of $8.9 billion this year," he said. In 2009, the world's airlines lost about $10 billion amid the global economic crisis. (Reuters)