The National Security Council sent a stern three-page warning to all the country’s newspaper editors detailing banned topics, including the rise in gasoline prices or other economic woes like possible new international sanctions, negotiations with the United States over the future of Iraq, civil society movements and the Iranian-American arrests.

The entire campaign is “a strong message by Ahmadinejad’s government, security and intelligence forces that they are in control of the domestic situation,” said Hadi Ghaemi, an Iran analyst for Human Rights Watch. “But it’s really a sign of weakness and insecurity.”

At least three prominent nongovernment organizations that pushed for broader legal rights or civil society have been shuttered outright, while hundreds more have been forced underground. A recent article on the Baztab Web site said that about 8,000 nongovernment organizations were in jeopardy, forced to prove their innocence, basically because the government suspects all of them of being potential conduits for some $75 million the United States has earmarked to promote a change in government.

Professors have been warned against attending overseas conferences or having any contact with foreign governments, lest they be recruited as spies. The Iranian-Americans are all being detained basically on the grounds that they were either recruiting or somehow abetting an American attempt to achieve a “velvet revolution” in Iran.

Analysts trace the broadening crackdown to a March speech by Ayatollah Khamenei, whose pronouncements carry the weight of law. He warned that no one should damage national unity when the West was waging psychological war on Iran. The country has been under fire, particularly from the United States, which accuses it of trying to develop nuclear weapons and fomenting violence in Iraq.

President Ahmadinejad and other senior officials have dismissed all the criticism as carping. The president blames the previous administration for inflation or calls it media exaggeration, while Tehran’s chief prosecutor, Said Mortazavi, said Iranians who oppose the Islamic Republic look for an excuse to criticize it.

After a meeting of senior police and judiciary officials in Tehran on June 19 to review what was described as “the public security drive,” the Iranian Labor News Agency quoted Mr. Mortazavi as saying that if the state did not protect public security, then “louts” and criminals “would be safe in society.