US Secretary of State Mike Pompeo on Friday slammed Iran for using "violence" and censorship to prevent memorials for those killed during the suppression of recent protests.

Protests broke out on November 15 across Iran, whose economy has suffered under sweeping sanctions from the United States, after the government abruptly hiked fuel prices.

"The Iranian people have the right to mourn 1,500 victims slaughtered by @khamenei_ir during #IranProtests," Pompeo tweeted, directly accusing Iran's supreme leader Ayatollah Ali Khamenei.

According to the Ilna news agency, internet access was effectively cut off Wednesday in multiple Iranian provinces ahead of memorials planned on social media a month after the protests.

"The regime fears its own citizens, and has once again resorted to violence and shutting down the internet," he added.

The United States said earlier this month that Iranian authorities may have killed more than 1,000 people in a crackdown on demonstrations in mid-November.

In his tweet, Pompeo cites to a much higher death toll that has already been listed by certain media outlets, as well as the exiled Mujahedin-e-Khalq, the formerly armed opposition that is fiercely critical of the regime and has cultivated close ties with the Trump administration.

Tehran has yet to publish its official death toll.

Human rights organization Amnesty International has confirmed that more than 300 people died during the protest crackdown.