The European Union demanded on Tuesday that privacy and health concerns over the use of body scanners be answered before it backed their mass introduction after the failed Christmas jet attack in the United States.
EU security experts are to meet in Brussels on Thursday to discuss the emergency measures ordered after a Nigerian tried to set off a bomb on a US jetliner arriving at Detroit airport on December 25.
Spain's transport minister said his country would not allow scanners until there is EU-wide agreement, though many countries around the world have already started body pat-downs and searches of carry-on baggage on flights heading for the United States and reported few delays.
Britain and the Netherlands have said they will introduce scanners, and Germany and Italy support tougher security, but the executive European Commission has insisted that privacy concerns must be answered.
The EU "considers body scanners, if they meet the health standards and security standards, as a useful additional tool providing they do not contradict existing European legislation," a commission transport spokeswoman said.
"They should be considered additional to other security measures," she said.
In Britain, privacy campaigners said the scanner images were so graphic they amounted to "virtual strip searching" and have called for safeguards to guard against indecent images of children getting onto the Internet.
Spanish Transport Minister Jose Blanco said Spain would not bring in "additional measures", such as scanners, without an EU agreement. He stressed that any new security measures must be "compatible" with the freedom and privacy of individuals.
The main health concerns are over the x-rays and electro-magnetic waves given off by the scanners. But many health experts say the risk is minimal.
Italian Foreign Minister Franco Frattini said safety was more important than concerns that full-body scanners, which can see through clothing, invade privacy.
"It is the most reliable instrument," Frattini, a former EU justice commissioner, added.
Even if the scanners meant a "sacrifice" for passengers' privacy, the "right to security is essential for all other freedoms", he said.
The United States has demanded compulsory extra security on all flights from 14 nations and random extra checks on flights from other nations.
Pakistan is one of the 14 nations singled out. However Sultan Hasan, spokesman for Pakistan International Airlines (PIA), said there had been "no resistance or protests" to the new security measures.
"In fact, they are very cooperative as they realise that we do all this for their own safety."
Lebanon is also on the list. The Arab-language An-Nahar daily, citing well-informed sources, said the decision to place Lebanon on the list was linked to security at Beirut airport, which is in the southern suburbs controlled by the Muslim militant group Hezbollah.
Brett Henry, vice president for marketing at Asia's leading air ticketing and reservations firm Abacus, said the new security may cause some inconvenience but it would not deter travel from Asia to the United States.
Henry highlighted the drastic changes already made since the September 11, 2001 attacks in the United States by Al-Qaeda.
"These measures may cause some hassle but they don't change the fact that commerce needs to go on, and friends need to meet with friends and families with families."
At Singapore's Changi Airport, many passengers agreed that the enhanced screening would make travel more difficult. Briton John Ras, 52, raised questions about whether pat-downs and body scans would prevent attacks.
Ras, a manager and frequent traveller to the United States, said: "It's a pain because it's useless... When I travel I get served wine in a glass bottle with a nice knife and a fork to eat my meals yet I can't take small scissors on my flight."
Thailand said it was planning to deploy body scanners at Bangkok's Suvarnabhumi airport on top of other additional security.
But airport general manager Nirandra Theeranartsin said only a small number of the 150,000 passengers handled each day were from the 14 countries targeted by the United States, and that there were few delays.
"So far the airlines have no complaints and they say the new security measures are acceptable to them," he said.
In Japan, US-bound passengers have been told to be at airports earlier. "Fortunately, we experienced no significant delays," said a spokesman for Japan Airlines, the country's biggest carrier.