The incident occurred on February 4, when an SMM patrol was en route from Luhansk to meet an SMM convoy coming from government-controlled Sievierodonetsk (90km west of Luhansk), the mission said in a situational report posted on OSCE website.
"At 11:06hrs [on Wednesday], when the SMM patrol en route from Luhansk was approximately 700 meters from the south end of Stanytsia Luhanska bridge [in “LPR”-controlled territory], three mortar rounds exploded," the report said.
"The SMM assessed that the mortars [possibly 82mm] came from a north-westerly direction," it said.
The Organization for Security and Cooperation in Europe Special Monitoring Mission has been deployed in eastern Ukraine at Kiev's request since last spring.
Despite a ceasefire agreement reached by the warring parties in September 2014, a surge of violence in eastern Ukraine has shown no signs of abating since the start of January.
A Kiev-led military assault on predominantly Russian-speaking independence supporters in the Donbas, which also encompasses the neighboring Donetsk region, dates back to mid-April 2014.
