As Iran’s government prepared this week to hold the funeral for its slain supreme leader that is expected to project an image of a country united in grief, its security services kept up a crackdown on dissidents and leaders in civil society.

On Wednesday, Iranian security forces arrested two well-known environmentalists, Houman Jokar and Sepideh Kashani, in their home and confiscated their electronic devices, their lawyer, Hojjat Kermani, told The New York Times. Ms. Kashani’s sister Sima, who has multiple sclerosis, was also arrested, Mr. Kermani said.

Mr. Kermani said no information had been released about the charges his clients face and he had yet to receive calls from them. He said the two activists had been able to speak to their parents briefly on Thursday.

Iran’s foreign ministry did not respond to a request for comment on the arrests. Iran’s official state media have not mentioned their detention, though the news has been covered by some reformist-leaning outlets.

The arrests are just a sliver of an ongoing, severe crackdown against Iranian civil society and dissidents, including the arrest of over 6,000 people since the launch of the U.S.-Israeli war on Feb. 28, according to Amnesty International.

Mr. Jokar dedicated much of his life to saving Iran’s endangered population of Asiatic cheetahs. He and Ms. Kashani were members of the Persian Wildlife Heritage Foundation, a Tehran-based group.

The two were last arrested in 2018, along with other environmental activists, and were held in Tehran’s Evin Prison by the intelligence arm of Iran’s Islamic Revolutionary Guards Corps. They were charged with spying, which they vehemently denied, and spent more than six years in prison before being released in 2024.

Niloufar Bayani, another Iranian environmental activist who was arrested in 2018, said in an interview this week that, since their release, none of the activists had been allowed to work in Iran.

“They have not taken part in any activities, whether environmental, political or social,” Ms. Bayani said. “This makes their rearrest even more concerning.”

Instead Mr. Jokar and Ms. Kashani had focused in recent years on rebuilding their personal lives and taking care of sick family members, Ms. Bayani said. The arrests, she added, send a message to environmentalists “that our mere existence, our identity as independent environmental experts, is illegitimate, and that we are in danger regardless of our actions.”

After Iran was rocked by nationwide demonstrations in January, calling for an end to its Islamic authoritarian system of rule, the government responded by killing thousands of protesters, according to human rights groups.

Since then, authorities have stepped up their use of the death penalty, particularly for people who participated in the protests, and have detained human rights activists. The government has used the war launched by the United States and Israel against Iran as one justification for the crackdown, accusing some protesters of collaborating with the two countries.

Analysts say that the government appears to be trying to use the funeral this week for Ayatollah Ali Khamenei to portray itself as having broad public support, even though there is widespread discontent over an economy in crisis and stifling repression.

President Masoud Pezeshkian this week urged Iranians “of every ethnicity, religion, preference and political tendency” to attend the public funeral ceremonies.

“The Islamic Republic speaks of the need for ‘national reconciliation,’” said Siamak Namazi, an Iranian-American man who was imprisoned in Iran for eight years and was cellmates with Mr. Jokar, in a social media post. “Explain how dragging away two of Iran’s finest people, along with a woman with MS. who was caring for her recovering father, without charges, without transparency, and without due process is reconciliation.”