Former Soviet leader Mikhail Gorbachev on Thursday called for the leaders of the United States and Russia to prevent further escalation of a violent standoff between demonstrators and police in Ukraine's capital, Kiev.
"I ask you to find a way to take a resolute step in helping Ukraine return to a peaceful path of development," Gorbachev said in a letter to Barack Obama and Vladimir Putin published on his website, Gorby.ru.
"We must not allow Ukrainians to fight Ukrainians," he said.
At least three demonstrators have died during rallies that began on Sunday in protest of hastily passed legislation curtailing the freedom of assembly in Ukraine.
Police have been accused of using excessive force, while rioters have been seen throwing flaming Molotov cocktails at police lines.
Gorbachev wrote that "now is not the time to investigate" the allegations both sides are making because doing so would "only complicate the situation."
He said the conflict in Ukraine is particularly hard on Russians, noting that many families have relatives from both countries. Both his late wife and mother were Ukrainian.