Iranian Kurds staged one of their largest strikes in recent years, closing shops and bazaars in nearly all Sunni Kurdish cities and towns in eastern Iran to protest the executions of five people, including four Kurdish activists, on Sunday, according to opposition Web sites and witnesses.

The strike was the largest in Kurdish areas since 2005, when another Kurdish activist was shot and killed by security forces.

Iran’s Kurds have long presented a delicate subject for the government, which fears that the restive population will join Kurds in Iraq and Turkey to try to form a Kurdish nation. Iran’s leadership has faced opposition from at least one armed separatist group.

Iran’s Kurds, mostly Sunni Muslims, are a minority in a mainly Shiite country, and they say the government discriminates against them.

Tehran’s sensitivity about the Kurds and other ethnic groups has only increased over the past year, as Iran’s leaders have faced their most serious political challenge since the Islamic Revolution, with tens of thousands of Iranians protesting a presidential election they declared fraudulent.

Many analysts and opposition figures interpreted the executions on Sunday as a warning that the government would not tolerate protests next month on the election’s first anniversary.

The government said the five people who had been executed had been found guilty of carrying out fatal bomb attacks.

Nearly all the shops were closed in Sanandaj, the capital of Kurdistan Province, said a witness who spoke on the condition of anonymity for fear of being arrested. “The city is deserted,” he said. “People have stayed home and the entire bazaar is closed.”

The shops and bazaars in several other Kurdish cities, including Bukan, Oshnavieh and Marivan, were also closed, an opposition Web site, Jaras, reported. Pictures and videos posted on Web sites appeared to support those claims.

Clashes with security forces in several towns were reported, but those accounts could not be independently confirmed.

“This is the first time in the past 30 years that we see such a solidarity between the Kurds and people in other parts of the country,” said a Kurdish activist, Saman Rasoulpour, who left Iran and is in Sweden.

Iranians have staged protests in Stockholm and Paris to protest Sunday’s executions. Mir Hussein Moussavi, an opposition leader, condemned the executions as “unfair.” He said that instead of executing the five activists when there were still so many unanswered questions about the case against them, the authorities should have been pursuing the crimes committed last summer against detainees who were arrested in the postelection protests. He was referring to rape allegations and the deaths of at least three detainees in prison.

The authorities have refused to give the bodies of the five executed activists to their families for burial, fearing that ceremonies could lead to protests.

In Kamyaran, the home city of Farzad Kamangar, a Kurdish teacher who was executed, parents did not send their children to school on Thursday and employees refused to go to work, according to Human Rights Activists News Agency, run by an opposition group. Mr. Kamangar’s family members were threatened and put under house arrest after they returned from Tehran, where they had tried to retrieve his body, the agency reported.

Jaras said five Kurdish students were arrested in Marivan on Thursday and seven others were summoned to Evin Prison.