WASHINGTON — The Iranian government, determined to limit Western influence and defend itself against cyberattacks, appears to have laid the technical foundations for a national online network that would be detached from the Internet and permit tighter control over the flow of information.

The concept of a self-contained network has been reverberating within Iran for almost a decade and has often been treated with skepticism, given the significant investment in infrastructure and security that would be required. But Iranian officials and outside experts say that development of the network has accelerated following cyberattacks aimed at the country’s nuclear program.

Last month, Iran’s communications and information technology minister unveiled a plan to take key government agencies and military outfits offline and onto the new network by the end of September. U.S. security researchers say they are for the first time seeing evidence of an operational network that is consistent with Iran’s publicly stated plans.

The researchers, working under the auspices of the University of Pennsylvania’s Center for Global Communications Studies, say in a report to be released this week that they have found functional versions of the sites of government ministries, universities and businesses on the network. They also found evidence of an already operational filtering capability.

At the core of the network was high-end equipment manufactured by the Chinese firm Huawei that is capable of sophisticated online surveillance of traffic. The network is already “internally consistent and widely reachable,” concluded the report, a copy of which was provided to The Washington Post.

William Plummer, vice president for external affairs at Huawei, said: “Huawei has not sold equipment to the Iranian government nor does it support monitoring traffic. Huawei only sells commercial equipment built to global standards to commercial operators.”

The findings are likely to worry Internet freedom activists and the Obama administration, which has spent tens of millions of dollars on initiatives designed to ease access to the Internet in Iran and other countries with repressive governments. Officials had expressed concerns even before the release of the latest research.

“We have concerns from not only a human rights perspective, but about the integrity of the Internet,” David Baer, deputy assistant secretary for the State Department’s Bureau of Democracy, Human Rights and Labor, said in an interview. “When countries section off parts of the Web, not only do their citizens suffer, everyone does.”

Experts say the Iranian government has a handful of reasons to establish a state-run alternative to the Internet. A protected Iran-only network could help officials counter U.S.-funded programs that allow Iranian activists to evade online surveillance. It could also help insulate Iranian computers from a covert campaign of cyberattacks that Iranian officials assert the United States and Israel continue to wage.

The Iranian network is not expected to entirely replace the Internet. But for ordinary Iranians it could be a well-run alternative to the Internet, which in Iran is often still accessed through dial-up connections.

Internet speeds in the country are intentionally suppressed to make certain Web activities, including the streaming of video, virtually impossible. Many Web sites, such as Facebook and YouTube, are blocked by the Iranian government.

Having the infrastructure for a skeleton Iran-only Internet in place would give the Iranian government greater power to shut off access to the Internet at times of civil unrest, such as the anti-government protests that swept Iran in 2009.

During the Arab Spring uprising in Egypt, President Hosni Mubarak’s regime tried to stall its spread by shutting off access to the Internet — a move that largely backfired when it caused panic. Having a national network operational could help prevent a similar outcome in Iran.

“The main reason for this project is security,” said Moussavi Khoeini, a former Iranian reformer and parliament member now living in exile. “They may say it’s to increase Internet speeds or protect against harmful content, but it’s always been security.”

Not all experts are convinced that an Iranian network would be viable, especially given the need for access to the Internet for commercial purposes and international communication.

“Any attempt by a country to make an intranet is doomed to failure,” Cedric Leighton, a retired deputy director at the National Security Agency, said in an interview.

But Leighton, who spent more than 25 years as an intelligence officer specializing in cybersecurity, said that Iran’s “cyber army,” a network of government-supported hackers that has attacked Western targets in recent years, does stand to gain from the attempted creation of a national network.

By “laying down the fiber” and connecting thousands of servers inside Iran, the government would “build on their knowledge of networks and how they operate,” he said, increasing their capabilities to both launch and repel cyberattacks.

“But no matter what you do, there will always be vulnerabilities in a network,” Leighton said.

Both the Obama administration and Internet freedom experts have expressed concern that the launch of the Iranian network could set a precedent for repressive governments across the globe. Reza Taghipour, Iran’s communications and information technology minister, has lauded Iran as a “pioneer” of the idea, hinting that other nations could follow his country’s lead.

“We don’t want governments to believe that it is now legitimate to take a country offline,” explained Brett Solomon, executive director of AccessNow.org, a global digital freedom initiative. “If we look back to the Egyptian revolution, where the regime shut down the free flow of information, you can see how this act could give rise to the creation of a new international norm.”

The researchers who uncovered the foundations of the new Iranian network said they found that it already hosted a number of Web sites — typically government or academic sites — meaning that the beginning of an Iranian Internet is already in operation.

E-mail and other providers are in place, and a scan of the network’s infrastructure by the researchers uncovered more than 10,000 devices connected to the system.

Collin Anderson, a Washington, D.C.-based security researcher and the report’s lead author, said the study should prompt further work on the scope of the Iranian network, its filtering ability, its growth, and how many Web sites were available only there.

“Internet freedom is a cat-and-mouse game — bad actors will always think of new ways to thwart the aspirations of the public,” Anderson said. “People and organizations have to remain vigilant to the ever-changing environment in order to support those who want to fight back against isolation.”