Four Ukrainian soldiers have been killed in the east of the country after they were fired on by pro-Russian separatists, government officials say.
Their vehicle was reportedly hit as it drove across a bridge in Schastye, close to the separatist stronghold of Lugansk.
Initial reports said rebels “had fired an anti-tank missile”, the interior ministry said in a statement.
A fragile ceasefire has been in force since February.
There have been isolated violations of the ceasefire, which was agreed by leaders from Ukraine, Russia, Germany and France.
On Saturday, the government reported the deaths of three soldiers in a mine explosion near Donetsk, another separatist stronghold.
Some 6,000 people have been killed since fighting broke out in eastern Ukraine between pro-Russian separatists and the Ukrainian government a year ago.
The Ukrainian government, Western leaders and Nato say there is clear evidence that Russia is helping the rebels with heavy weapons and soldiers. Independent experts echo that accusation.
Moscow denies it, insisting that any Russians serving with the rebels are “volunteers”.