UN rights chief Michelle Bachelet told Iran on Friday to address with the chronic water shortage in Khuzestan province rather than use excessive force to crush protests.
Bachelet warned that the "catastrophic" situation had been building up for many years and that "shooting and arresting people will simply add to the anger and desperation".
"I am extremely concerned about the deaths and injuries that have occurred over the past week, as well as the widespread arrests and detention," AFP quoted Bachelet as saying in a statement.
"The impact of the devastating water crisis on life, health and prosperity of the people of Khuzestan should be the focus of the government's attention, not the protests carried out by people driven to desperation by years of neglect."
Bachelet's office said Khuzestan used to be Iran's main and most reliable source of water, but alleged mismanagement coupled with droughts had drained the province.
Protests erupted on July 15 in several cities across the province. In response, state security forces appear to have reacted with disproportionate force against unarmed, peaceful protesters, her office said.
At least four people, including one minor, have been killed, and several others injured, while three are unconfirmed reports of a higher number of deaths, said the Office of the High Commissioner for Human Rights.
State media has reported that one police officer has been killed.
Bachelet said: "When you hear reports that injured protesters are avoiding hospitals for fear of being arrested, it is an indication of just how bad the situation is."
The high commissioner said Iran lacked effective channels for people to raise their grievances other than through protest, citing severely restricted civic space and a lack of a free media.
"The government of Iran desperately needs to change tack, beginning with issuing clear instructions to security forces to abide by international standards on the use of force," the former Chilean president said.
"It should also take immediate steps to first of all mitigate the impact of the crisis and to put in place policies that can ensure the right to water in Khuzestan in the long term."
