on the issue to be held no later than May 11. While none of the self-appointed leading figures in the Donetsk Republic movement has said they necessarily want the region to join Russia, they have also declined to rule out the option.
Despite claims by the autonomy groups to represent the entirety of Donetsk, a region of more than 4 million people, rallies outside the regional administration building have since the weekend drawn crowds only in the low thousands.
In a third eastern city, Luhansk, pro-Russia groups remained in control of the local branch of the security services, which they seized over the weekend. There have been no attempts to recapture the building.
The Luhansk police chief called on protesters to surrender their guns and said parliament was considering an amnesty that would be extended to them.
The seizures of the buildings and calls for referenda were an echo of the events that led to Russia's annexation of Ukraine's Crimean peninsula last month. After Yanukovych fled to Russia, Russian troops took control over Crimea and the region voted to join Russia in a hastily called referendum.
The West has not recognized the vote or the annexation and has retaliated with sanctions against Russia.
Even as the United States warned Russia of further sanctions if Moscow takes further efforts to destabilize Ukraine, the White House announced Tuesday a high-level meeting among U.S., EU, Ukrainian and Russian diplomats in the coming days to try to solve the crisis.
Russia's Foreign Minister Sergey Lavrov said in Moscow on Tuesday that the date and format of the four-way talks haven't yet been agreed. He suggested that Ukraine's presidential candidates could be invited to join the negotiations and emphasized the need for the regions to take part in drafting Ukraine's constitutional reform.
The Kremlin has pushed for a constitutional reform in Ukraine that would turn it into a federation with broad powers for its regions and ensure the country's neutrality - demands that reflected Russia's desire to maintain influence over its neighbor and prevent it from joining NATO.