U.S. and Israeli companies are supplying sophisticated surveillance technology to Central Asian nations with records of widespread human rights abuses, giving state security services virtually unchecked power to monitor the communications of ordinary citizens, according to a new report by Privacy International.

Researchers for the watchdog group, based in London, allege that the spy gear sold by these companies is key to the functioning of police states that smother the exercise of free speech, political dissent and other basic rights, while helping authoritarian governments maintain their grip on power.

The report, which was slated for release Thursday, offers detailed accounts of the functioning of surveillance systems in Kazakhstan, Uzbekistan and other Central Asian countries. It also singles out several companies for their roles in supplying the technology, including Verint Systems, based in Melville, N.Y.; Netronome, based in Santa Clara, Calif.; and Nice Systems, based in Israel.

“The brutal secret police of authoritarian states have been empowered with sweeping surveillance capabilities, aimed at putting the private lives of every individual within their reach,” report co-author Edin Omanovic said in a prepared statement. “This is exactly the kind of nightmare scenario that becomes inevitable when you have an unaccountable industry operating under the radar.”

The findings in the report, which rely on contracting documents and confidential sources, are difficult to independently verify. Efforts to reach representatives of the countries and some of the companies named in the report, including Verint and Netronome, were unsuccessful. Nice issued a statement: “NICE Systems sells its solutions only to nations with which the State of Israel allows trade relations. NICE is not in a position to provide additional comment on its relationships with actual or possible customers.”

The multibillion-dollar surveillance industry has boomed since the Sept. 11, 2001, terrorist attacks, with technology sold aggressively in regular trade shows around the world. Privacy advocates have sought to spotlight what they consider the role of these vendors in exporting the tools of government repression, especially in countries that have few protections against abuse.

Privacy International, which for several years has quietly collected marketing brochures from the typically secretive surveillance industry and posted them publicly on the Web, gained uncommonly detailed accounts of monitoring systems in Kazakhstan and Uzbekistan. The report features pictures of facilities — including interior rooms — that reportedly house surveillance systems.

The researchers detail how government security services — in many ways little changed in the years since these nations gained independence from the Soviet Union in 1991 — tap directly into communications networks to eavesdrop on a mass scale.

Authorities can read e-mails, listen to calls and track Web-site visits, all from decentralized networks of offices situated throughout each country. There also are larger monitoring centers equipped with the most powerful surveillance technology, including systems capable of “deep-packet inspection” that scan Internet traffic for particular words or phrases.

The report includes accounts from human rights activists, journalists and political exiles who say that their private communications and social-media postings had been intercepted by the government. In some cases, conversations conducted over Skype were later discovered by police, who reportedly showed transcripts to people during subsequent questioning.

Verint and Nice outfit and maintain these nations’ most sophisticated monitoring centers — sometimes in different offices of the same buildings — and do so with the approval of the Israeli government, Privacy International says.

Though Verint, which bills itself as a world leader in “actionable intelligence,” is based in the United States, most of its surveillance operations are in Israel. Verint also is a leading supplier of a type of location tracking technology that allows government officials to map the movements of individual cellphone users, even when they are traveling on different continents, by intercepting the location data that flows through international telecommunications networks.

Netronome provides technology intended to defeat encryption with fake digital certificates, allowing authorities to launch what experts call “man-in-the-middle attacks” that can reveal private communications. These potentially include communications through services offered by Google, Facebook and Microsoft, all of which have made major investments in encryption technology since the revelations of high-tech surveillance made by former National Security Agency contractor Edward Snowden.

Some Russian and German companies also supply some monitoring technology, and companies in the Central Asian nations help procure it, according to Privacy International.