Ukraine crisis: Kiev and rebels trade blame over Donetsk shelling
Ukraine's military and pro-Russian separatists have accused each other of shelling central areas of the main rebel stronghold of Donetsk.
The rebels claimed that one civilian died in the overnight attacks. Ukraine said the separatists themselves opened fire on the city.
International observers on the ground voiced concern over "a serious increase in tension" in Donetsk.
These were the first such attacks on central Donetsk since a February truce.
In other developments on Sunday:
- Ukrainian officials said four civilians were killed by rebel shelling of government-held towns in the Donetsk region in the past 24 hours
- rebel leaders said they unilaterally began withdrawing weapons under 100mm (4 inches) calibre from the line of contact. Ukraine and monitors from the Organization for Security and Co-operation in Europe (OSCE) have not commented on the claim
The Ukrainian government, Western leaders and Nato all say there is clear evidence that Russia is helping the rebels in the eastern Donetsk and Luhansk regions with heavy weapons and soldiers. Independent experts echo that accusation.
Moscow denies it, insisting that any Russians serving with the rebels are volunteers.
More than 6,400 people have been killed in fighting in eastern Ukraine that began in April 2014 when rebels seized large parts of the two eastern regions. This followed Russia's annexation of the Crimea peninsula.
'Intercepted radio traffic'
Eyewitnesses in Donetsk spoke of heavy bombardment of the central parts of the city on Saturday evening and overnight.
A video posted on the internet allegedly showed shells landing on several buildings and a fire in the city.
"Last time the centre of Donetsk was hit was in February," senior rebel official Eduard Basurin told Reuters news agency.
"I have no explanation. The Ukrainian side says we shelled ourselves. Do you believe we can shell ourselves?" he added.
He was speaking after Ukrainian military official Serhiy Halushko said the army had intercepted and posted online rebel radio traffic that suggested the separatists had planned to shell Donetsk.
In a BBC interview, OSCE deputy chief monitor Alexander Hug confirmed that "there was a serious increase in tension yesterday (Saturday) evening and night".
"[The shelling] was being conducted from within the city of Donetsk firing towards the west, towards (the) position of the Ukraine armed forces, as well as returned fire from this position into the city of Donetsk," he added.