Tensions in Ukraine eastern regions
Ukraine's government struggled to stay in control of the country's eastern regions as tensions flared in three cities.
While the government managed to recapture its regional headquarters and detain dozens of pro-Russian protesters in one city, it said "radicals" were keeping 60 people hostage and threatening them in another city.
Unknown "separatists" brandishing arms and explosives were threatening the hostages inside a security service branch in the city of Luhansk, the Ukrainian Security Service said in a statement.
It was not clear who the hostages were or if they were security service employees. The building was seized on Sunday by armed pro-Russian protesters.
Earlier on Tuesday, Ukrainian authorities battled with pro-Russian protesters but regained control over a government building in Kharkiv, the country's second-largest city, evicting the protesters and detaining dozens.
In Donetsk, a city 250 kilometres (155 miles) further south, protesters dug in for their third day at the 11-storey regional administration headquarters and began to declare their own parallel government.
Serhiy Taruta, the governor of Donetsk, scoffed at the shifting events in his city.
Pro-Russian activists with Russian flag sitting at a barricade at the regional administration building in Donetsk, Ukraine, Tuesday, April 8, 2014 (AP Photo/Efrem Lukatsky)
"I call this a theatre of the absurd," he said. "It is just artists performing, but the main thing is that there is an ever-dwindling audience."
All three cities are in Ukraine's east, where hostility is strong towards the government that took power in February after the removal of Kremlin-friendly president Viktor Yanukovych. Even though Ukraine's interim authorities have achieved some success in quelling unrest that swept across eastern provinces on Sunday, festering discontent threatens to undermine plans to hold a presidential election on May 25.
Addressing parliament in Kiev, acting president Oleksandr Turchynov said security forces retook control of the Kharkiv administration building early on Tuesday and several police were injured in the clashes with separatists.
Interior minister Arsen Avakov described the measure on his Facebook page as an "anti-terrorist operation".
In a session briefly interrupted by a brawl, parliament also voted to toughen punishment for undermining Ukraine's national security, imposing jail terms of up to five years for separatism.
In Donetsk, there was little sign on Tuesday afternoon that government forces had any immediate plan to clear the regional administration building. The city has seen weekly rallies marching on local government offices, but on Sunday groups of masked men carrying batons burst through police lines to take over the building.
Pro-Russian activist wears a hand-made mask behind a barricade in front of the regional administration building in Donetsk, Ukraine, Tuesday, April 8, 2014 (AP Photo/Efrem Lukatsky)
By Tuesday, lines of car tyres wrapped in razor wire had been erected as deterrent against a possible attempt by police to storm the premises. The tactic appears to have been copied from the anti-government protests in the capital, Kiev, which led to Mr Yanukovych's overthrow. Just like in Kiev, food stations have been created inside the Donetsk administration building, supplied by volunteers and local residents.
No clear leader or agenda has emerged from the obscure group of pro-Donetsk autonomy activists behind the stand-off.
A declaration adopted on Monday claimed sovereignty for what activists called the "Donetsk Republic" and called for a referendum on the issue to be held no later than May 11. While none of the self-appointed protest leaders 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 all of Donetsk, a region of more than four million people, rallies outside the regional administration building have since the weekend drawn crowds only in the low thousands.
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 Mr Yanukovych fled to Russia, Russian troops took control over Crimea and the region voted to join Russia in a hastily called referendum.
Pro-Russian activists control a barricade in front of the regional administration building in Donetsk, Ukraine, Tuesday, April 8 (AP Photo/Efrem Lukatsky)
The West has not recognised the vote or the annexation and has retaliated with sanctions against Russia.
Even as the United States warned Russia of more sanctions if Moscow takes further efforts to destabilise Ukraine, the White House announced on Tuesday a high-level meeting among US, EU, Ukrainian and Russian diplomats in the coming days to try to solve the crisis.
In Moscow, Russia's foreign minister Sergey Lavrov said that the date and format of the four-way talks have not yet been agreed. He suggested that Ukraine's presidential candidates could be invited to join the negotiations and emphasised 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 neighbour and prevent it from joining Nato.