"I am deeply disturbed by reports of violence during nationwide protests in Iran over the past 13 days, including reported deaths and destruction of property," UN Human Rights chief Volker Türk said in a statement on Friday.
"The right to peaceful protest, as enshrined in international law, must be protected. All deaths should be promptly, independently, and transparently investigated. Those responsible for any violations must be held to account in line with international norms and standards."
Türk said he is concerned by reports of nationwide internet and communications shutdowns.
"Such actions undermine freedom of expression and access to information, as well as impacting on the work of those documenting human rights violations, and access to essential and emergency services."