After taking control in Donetsk, with several thousand people occupying the main administrative building, the group released a video declaring their independence. "Seeking to create a popular, legitimate, sovereign state, I proclaim the creation for the sovereign state of the People's Republic of Donetsk," the spokesperson said, as the watching crowd reportedly cheered.
The unidentified man called for assistance from Moscow, saying, "Without your support, without the support of Russia, it will be hard for us to resist the Kiev junta on our own."
From Kiev, the interim Prime Minister Arseny Yatseniuk on Monday morning blamed the upheaval on Russian interference.
"The plan is to destabilize the situation, the plan is for foreign troops to cross the border and seize the country's territory, which we will not allow," Yatseniuk said.
According to Reuters:
The protesters appeared to be responding in part to Yanukovich, who fled to Russia after he was ousted and who on March 28 issued a public call for each of Ukraine's regions to hold a referendum on its status inside the country.
Separately, Ukraine's defense ministry said a Russian marine had shot and killed a Ukrainian naval officer in Crimea on Sunday night.
The 33-year-old officer, who was preparing to leave Crimea, was shot twice in officers' quarters in the locality of Novofedorovka. It was not clear why the Russian marine had opened fire.
Yatseniuk said that though much of the unrest had died down in eastern Ukraine in the past month there remained about 1,500 "radicals" in each region who spoke with "clear Russian accents" and whose activity was being coordinated through foreign intelligence services.
But he said Ukrainian authorities had drawn up a plan to handle the crisis.
"We have a clear action plan," he said, adding that senior officials would head to the towns concerned.
Meanwhile, news from Crimea on Sunday revealed that a Ukrainian military officer had been shot and killed by a Russian soldier. And though the incident appeared to result from a drunken brawl, observers on all sides have warned that it could be just such an incident of violence that could quickly escalate tensions between Kiev, Moscow, and the western powers that have continued to cast the situation in Ukraine in "Cold War" terms.