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.