The statement from Viktor Yanukovych, the former Ukrainian president who fled to Russia last month after three months of protests, raised the threat of more unrest in Ukraine's Russian-speaking eastern provinces, where many resent the new Ukrainian government.
Also Friday, Russian Defense Minister Sergei Shoigu told Putin the Ukrainian military withdrawal from Crimea was complete. Ukrainian soldiers were seen carrying duffel bags and flags as they shipped out of the Black Sea peninsula that Russia has annexed.
While Yanukovych has practically no leverage in Ukraine, his statement clearly reflected the Kremlin's focus on supporting separatist sentiments in eastern Ukraine.
The White House said that Putin called Obama Friday to discuss a U.S. proposal for a diplomatic resolution to the crisis in Ukraine, which U.S. Secretary of State John Kerry presented to Russian counterpart Sergey Lavrov earlier this week. Obama suggested that Russia put a concrete response in writing and the presidents agreed that Kerry and Lavrov would meet to discuss the next steps.
“President Obama noted that the Ukrainian government continues to take a restrained and de-escalatory approach to the crisis and is moving ahead with constitutional reform and democratic elections, and urged Russia to support this process and avoid further provocations, including the buildup of forces on its border with Ukraine,” the White House said in a statement.
A White House official, who wasn't authorized to comment by name and demanded anonymity, said that Obama and Putin spoke for an hour. He said the plan was the old off-ramp roadmap that had been drafted before Russia annexed Crimea last week.
The Kremlin said in its account of the conversation that Putin talked about action by extremists in Ukraine and suggested “possible steps by the international community to help stabilize the situation” in Ukraine. It added that Putin also pointed at an “effective blockade” of Moldova's separatist region of Trans-Dniester, where Russia has troops. Russia and the local authorities have complained of Ukraine's recent moves to limit travel across the border of the region on Ukraine's southern border. There were fears in Ukraine that Russia could use its forces in Trans-Dniester to invade.
Deep divisions between Ukraine's Russian-speaking eastern regions, where many favor close ties with Moscow, and the Ukrainian-speaking west, where most want to integrate into Europe, continue to fuel tensions.
The Crimean Peninsula, where ethnic Russians are a majority, voted this month to secede from Ukraine before Russia formally annexed it, a move that Western countries have denounced as illegitimate. Talk percolates of similar votes in other Ukrainian regions with large Russian populations, although none has been scheduled.
Russia has pushed strongly for federalizing Ukraine – giving its regions more autonomy – but Ukraine's interim authorities in Kiev have rejected such a move. The one vote that has been scheduled is a presidential election on May 25.
“Only an all-Ukrainian referendum, not the early presidential elections, could to a large extent stabilize the political situation and preserve Ukraine's sovereignty and territorial integrity,” Yanukovych said in a statement carried by the ITAR-Tass news agency.
He didn't specify what the vote should ask or when it should be held.
Russia's state RIA-Novosti news agency quoted Alexei Mukhin, a Kremlin-connected political analyst, as saying while a nationwide referendum would be difficult to organize in each of Ukraine's provinces, the country's southeastern regions could follow Yanukovych's advice.
In Kiev, Ukrainian prosecutors opened a new investigation against Yanukovych on charges of making calls to overthrow the country's constitutional order. He already is being investigated in the deaths of dozens of Ukrainian protesters who were shot dead in Kiev in February.
Yanukovych's old rival, former Prime Minister Yulia Tymoshenko, attacked his statement, accusing him of being “a tool aimed at destroying the independence of Ukraine.”
Tymoshenko is running in Ukraine's next presidential election, which Russia has sought to delay.
The new Ukrainian government and the West, meanwhile, have voiced concerns about a possible invasion as Russia builds up its troops near the border with Ukraine. Putin has warned that Russia could use “all means” to protect people in Ukraine from radical nationalists.
However, U.N. Secretary-General Ban Ki-moon said Friday that Putin had assured him he had no intention of making another military move into Ukraine.
That was echoed by Russia's U.N. Ambassador Vitaly Churkin, who said Putin made clear in a March 18 statement that there was not going to be any new Russian move into Ukraine.
While Putin has said Russia doesn't want a division of Ukraine, he also sought to cast it as an artificial state created by the Communists that includes historic Russian regions – controversial statements that raise doubts about the Kremlin's intentions.
To tamp down those fears, the Russian Foreign Ministry said Friday that Moscow allowed observation flights over the border by Ukrainian, U.S., German and other Western officials. It said if any major troop concentrations had been spotted, the West wouldn't have been shy to speak about it.
Russia also kept pushing its long-held contention that ethnic minorities in Ukraine are living in fear of the new interim authorities. The Foreign Ministry said not just ethnic Russians, but ethnic Germans, Hungarians and Czechs in Ukraine also are feeling in peril.
“They are unsettled by the unstable political situation in the country and are seriously afraid for their lives,” the statement said, without citing specific incidents.
However, there have been no signs of such threats toward ethnic minorities in Ukraine.
Russia also said it has responded anew to Western sanctions over Ukraine but did not make any new names public.
Russian Foreign Ministry spokesman Alexander Lukashevich said some Western nations have followed the U.S. example and expanded their sanctions against Russia, adding that Moscow has taken “retaliatory measures, which are largely tit-for-tat.” He wouldn't say who the latest targets were.
The United States, the European Union and Canada have slapped Russia with travel bans and asset freezes targeting its officials and lawmakers over the annexation of Crimea.
Associated Press writer Josh Lederman in Washington contributed to this report.