China and Southeast Asian governments demanded an explanation from US and its allies on Thursday following media reports that American and Australian embassies in the region were being used as hubs for Washington's secret electronic data collection program.
The reports come amid an international outcry over allegations the US has spied on the telephone communications of as many as 35 foreign leaders.
A document from National Security Agency leaker Edward Snowden, published this week by German magazine Der Spiegel, describes a signals intelligence program called "Stateroom" in which US, British, Australian and Canadian embassies secretly house surveillance equipment to collect electronic communications.
Those countries, along with New Zealand, have an intelligence-sharing agreement known as "Five Eyes."
"China is severely concerned about the reports, and demands a clarification and explanation," Chinese Foreign Ministry spokeswoman Hua Chunying said.
Australia's Fairfax media reported Thursday that the Australian embassies involved are in Jakarta, Bangkok, Hanoi, Beijing and Dili in East Timor; and High Commissions in Kuala Lumpur and Port Moresby, Papua New Guinea.
The Fairfax report, based on the Der Spiegel document and an interview with an anonymous former intelligence officer, said those embassies are being used to intercept phone calls and internet data across Asia.
In a statement, Indonesia's Foreign Minister Marty Natalegawa said his government "cannot accept and strongly protests the news of the existence of wiretapping facilities at the US Embassy in Jakarta."
"It should be emphasized that if confirmed, such action is not only a breach of security, but also a serious breach of diplomatic norms and ethics, and certainly not in tune with the spirit of friendly relations between nations," he said.
The Snowden document said the surveillance equipment is concealed, including antennas that are "sometimes hidden in false architectural features or roof maintenance sheds."
Des Ball, a top Australian intelligence expert, told The Associated Press he had personally seen covert antennas in five of the embassies named in the Fairfax report.
He declined to go into further detail or specify which embassies those were.
But Ball said what Der Spiegel has revealed is hardly surprising or uncommon.
Many countries have routinely used embassies as bases to covertly listen in on phone calls, and reports of such surveillance have been public for decades, he said.
"We use embassies to pick up stuff that we can't pick up from ground stations here in Australia - and lots of countries do that," said Ball, a professor with the Australian National University's Strategic and Defence Studies Centre.
According to the Snowden document, the spying sites are small in size and staff.
"They are covert, and their true mission is not known by the majority of the diplomatic staff at the facility where they are assigned," it said.
The Department of Foreign Affairs and Trade declined to comment on the reports. Australian Prime Minister Tony Abbott said only that the government had not broken any laws.
"Every Australian governmental agency, every Australian official, at home and abroad, operates in accordance with the law," Abbott told reporters. "And that's the assurance that I can give people."
Still, there was predictable outrage in the countries named in the document.
Malaysian home minister Ahmad Zahid Hamidi said his government viewed the allegations as a serious matter and would investigate whether the US Embassy in Kuala Lumpur was being used for spying.
The country's opposition party issued a statement Thursday urging the Malaysian government to lodge a protest with both the US and Australian embassies.
Thailand's National Security Council Secretary-General, Lt. Gen. Paradorn Pattanathabutr, said the government told the US that spying was a crime under Thai laws, and that Thailand would not cooperate if asked to help eavesdrop.
Asked about the Australian embassy allegations, he said Australians are not capable of doing such sophisticated surveillance work.
"When it comes to technology and mechanics, the US is more resourceful and more advanced than Australia," he said. "So I can say that it is not true that the Australian embassy will be used as a communications hub for spying."