A police officer is among the two people killed in a bomb explosion at a march in Ukraine's second-largest city Kharkiv, officials say.
Police have detained an unspecified number of suspects following a bomb attack at a peace march in Ukraine which left two people dead, authorities say.
At least two people have been killed after an explosive device was thrown from a car into a crowd attending a peace rally in Ukraine, officials say.
Police said 15 people have also been wounded in the incident in Ukraine's second-largest city Kharkiv, which lies just outside the conflict zone.
An unnamed regional prosecutor quoted by Reuters said three were killed but the figure was later revised to two.
Television footage showed emergency service workers carrying a body into the back of an ambulance in the aftermath of the attack.
At least one person has died and multiple others have been wounded after an explosion at a peace march in the Ukrainian city of Kharkiv, officials say.
Ukrainian police said it was being treated as a "terrorist act" after an an "unknown explosive device" was found.
The march was one of several events marking the deaths of protesters who died during an uprising against the former pro-Russian president Viktor Yanukovych last year.
The reported explosion comes amid efforts to maintain a ceasefire between Ukrainian government troops and pro-Russian separatists.
Russia will face more sanctions if they continue to "destablise" Ukraine, William Hague has said.
The former Foreign Secretary told the BBC that Russian President Vladimir Putin is facing a "huge long-term price" for his country's alleged role in supporting separatists in eastern Ukraine.
"The costs to Russia over this behaviour are mounting and will get even higher," he told the BBC.
"If Russia continues to destabilise Ukraine there will be higher sanctions."
Mr Hague said the UK was not planning to send arms to the Ukrainian government following calls from ex-defence secretary Liam Fox.
"We are not planning to send arms to Ukraine - we want to see a diplomatic solution. You have to think very carefully before you send arms into a conflict."
Pro-Russian separatists have agreed to start the withdrawal of heavy weapons in eastern Ukraine, a senior rebel commander has said.
"The plan was signed last night, starting from today there are two weeks to withdraw heavy weapons," Eduard Basurin was quoted as saying by Russian news agency Interfax.
It comes as government forces and separatists exchange dozens of prisoners as part of the internationally brokered ceasefire deal.
Yesterday, US Secretary of State John Kerry said the US and Europe were discussing potential further sanctions against Russia after several breaches of the truce were reported.
Ukrainian military and separatist representatives have exchanged dozens of prisoners at a remote frontline location, kicking off a process intended to usher in peace to the conflict-ridden east.
The prisoner swap saw 139 Ukrainian troops and 52 rebels exchanged at a no man's land location near the village of Zholobok, some 12 miles west of the rebel-held city Luhansk.
A busload of Ukrainian soldiers in military fatigues was transported earlier in the day from the main rebel stronghold of Donetsk to a rural spot some 90 miles to the north-east, before joining up with other groups of fellow captives.
The peace agreement signed last week in Minsk foresees an exchange of all prisoners in the conflict.
It is unclear how many are held in total on both sides, although the Donetsk separatists have said Ukraine is holding about 580 rebels as prisoners.
President Barack Obama will evaluate the next steps in dealing with the conflict in eastern Ukraine in the coming days, including arming Ukrainian forces and sanctions against Moscow, US Secretary of State John Kerry said in talks in London today.
He said in a news conference: "In the next few days I anticipate that President Obama will evaluate the choices that are in front of him and will make his decision as to what the next step will be.
"There are serious discussions taking place between us and our European allies as to what those next sanctions steps are to be and when they ought to be implemented".
Thousands of Russians are marching in Moscow to mark the first anniversary of what they viewed as a "coup" in neighbouring Ukraine.Read the full story ›
The US and Europe are not prepared to play games with Russia over the Ukraine crisis, John Kerry has said.
Speaking alongside Foreign Secretary Philip Hammond, the US Secretary of State said additional sanctions could be imposed on Russia over its "simply unacceptable" alleged role in supporting separatists in eastern Ukraine.
"Russia has engaged in an absolutely brazen and cyclical process over these last days," he told reporters in London.
"We are talking about additional sanctions, about additional efforts, and I'm confident over the next days people will make it clear that we are not going to play this game and be part of this kind of extraordinarily craven behaviour.
"This is behaviour that is completely counter to everything that the global community has worked to achieve since World War II."