UN Secretary-General Antonio Guterres condemned on Sunday the "use of deadly violence" in Myanmar, calling on all parties to respect election results and return to civilian rule.

"The use of lethal force, intimidation & harassment against peaceful demonstrators is unacceptable," the UN chief said via Twitter.

Two people were killed on Saturday in Myanmar's Mandalay as police used tear gas and rubber bullets to disperse demonstrators.

Since early this month, protests have been held in the country calling for the release of the detained leaders, including U Win Myint and Aung San Suu Kyi.