Technology entrepreneur Jerry Lucas hosted his first trade show for makers of surveillance gear at the Hilton in suburban McLean, Va., in May 2002. Thirty-five people attended.

Nine years later, Lucas holds five events annually across the world, drawing hundreds of vendors and thousands of potential buyers for an industry that he estimates sells $5 billion of the latest tracking, monitoring and eavesdropping technology each year. Along the way these events have earned an evocative nickname: The Wiretappers’ Ball.

The products of what Lucas calls the “lawful intercept” industry are developed mainly in Western nations such as the United States but are sold throughout the world with few restrictions. This burgeoning trade has alarmed human rights activists and privacy advocates, who call for greater regulation because the technology has ended up in the hands of repressive governments such as those of Syria, Iran and China.

“You need two things for a dictatorship to survive: propaganda and secret police,” said Rep. Christopher Smith, R-N.J., who has proposed bills to restrict the sale of surveillance technology overseas. “Both of those are enabled in a huge way by the high-tech companies involved.”

But the overwhelming U.S. government response has been to engage in the event as not a potential regulator but a customer.

The list of attendees for this year’s U.S. Wiretappers’ Ball, held in October at the North Bethesda, Md., Marriott Hotel and Conference Center, included more than 35 federal agencies, said Lucas. The list, he added, included the FBI, the Secret Service and every branch of the military, along with the IRS, Agriculture Department and the Fish and Wildlife Service. None would comment on their participation in the event.

Representatives of 43 countries also were there, Lucas said, as were many people from state and local law enforcement agencies. Journalists and members of the public were excluded.

On offer were products that allow users to track hundreds of cellphones at once, read emails by the tens of thousands, even get a computer to snap a picture of its owner and send the image to police or anyone else who buys the software. One product uses phony updates for iTunes and other popular programs to infiltrate personal computers.

The Commerce Department regulates exports of surveillance technology, but its ability to restrict the trade is limited. Intermediaries sometimes redirect sales to foreign governments, even those subjected to economic sanctions, once products leave the United States. The State Department, which has spent $70 million in recent years to promote Internet freedom abroad, has expressed rising alarm over such transactions but has no enforcement authority.

U.S. law generally requires law enforcement agencies to obtain court orders when intercepting domestic Internet or phone communications. But such restrictions do not follow products when they are sold overseas.

Industry officials say their products are designed for legitimate purposes such as tracking terrorists, investigating crimes and allowing employers to block pornographic and other restricted websites at their offices.

“This technology is absolutely vital for civilization,” said Lucas, president of TeleStrategies, which hosts the events, officially called Intelligent Support Systems World Conferences. “You can’t have a situation where bad guys can communicate and you bar interception.”

But the surveillance products themselves make no distinction between bad guys and good guys, only users and targets. Several years of industry sales brochures provided to The Washington Post by the anti-secrecy group WikiLeaks, and released publicly Thursday, reveal that many companies are selling sophisticated tools capable of going far beyond conventional investigative techniques.

“People are morally outraged by the traditional arms trade, but they don’t realize that the sale of software and equipment that allows oppressive regimes to monitor the movements, communications and Internet activity of entire populations is just as dangerous,” said Eric King of Privacy International, a London-based group that seeks to limit government surveillance. Sophisticated surveillance technology “is facilitating detention, torture and execution,” he said.

Demand for surveillance tools surged after the Sept. 11, 2001, attacks as rising security concerns coincided with the spread of cellphones, Skype, social media and other technologies that made it easier for people to communicate, and easier for governments and companies to eavesdrop on a mass scale.

The surveillance industry conferences are in Prague, Czech Republic; Dubai, United Arab Emirates; Brasilia, Brazil; the Washington area; and Kuala Lumpur, Malaysia, whose event starts Tuesday. They are invitation-only affairs, and Lucas said he bars Syria, Iran and North Korea, which are under sanctions.

The most popular conference, with about 1,300 attendees, was in Dubai this year. Middle Eastern governments, for whom the Arab Spring, the protests and demonstration that started in 2010, was “a wake-up call,” are the most avid buyers of surveillance software and equipment, Lucas said. Any customers attending are free to buy products there.

“When you’re selling to a government, you lose control of what the government is going to do with it,” Lucas said. “It’s like selling guns to people. Some are going to defend themselves. Some are going to commit crimes.”

The suppliers are global as well. About 15 of the vendors for the conference in Bethesda were based in the United States, said Lucas. Others were from Germany, Italy, Israel, South Africa and Britain; many of these also have U.S. offices targeting the market for law enforcement agencies and other government buyers.

Of the 51 companies whose sales brochures and other materials were obtained and released by WikiLeaks, 17 have secured U.S. government contracts in the past five years for agencies such as the FBI, the State Department and the National Security Agency, according to a Washington Post analysis of federal procurement documents.

Federal agencies declined to comment on the use of surveillance technology. But Lucas said that the Fish and Wildlife Service uses monitoring gear to catch poachers, the Agriculture Department to investigate abuse of grants and the IRS to search for evidence that tax filers have understated their income.

“The IRS love to find people filing zero income on their tax returns with photos of Ferraris on their Facebook pages,” Lucas said.

The number and scope of new devices coming on the market have astounded privacy advocates and human rights activists.

They include:

n A German company, DigiTask, offers a suitcase-sized device capable of monitoring the Web traffic of users at public WiFi hotspots such as cafes, airports and hotel lobbies.

n A British company, Cobham, creates bogus cell towers that lets users track phones up to three miles away and listen to some calls.