According to the OSCE report, artillery fire was registered on Thursday when the monitors visited the area outside the town of Novoaydar located 60 kilometers (37 miles) away from Luhansk. Some 20 shots were also heard by the monitors when they visited the town of Irmino, 35 miles away from Luhansk.
Ukraine's eastern regions have been suffering from armed confrontation since April 2014 when Kiev launched a military operation against the independence supporters of the country's east.
A ceasefire was reached in September 2014 with the mediation of Russia and the Organization for Security and Co-operation in Europe (OSCE). However, the warring sides failed to observe the truce and in the beginning of 2015 hostilities in Ukraine intensified.
On February 12, the leaders of Russia, Ukraine, Germany and France worked out a peace deal after 16-hour talks in the Belarusian capital of Minsk. The ceasefire came into force on February 15.
Several truce violations have been reported since then, but the OSCE monitors in the country said that the truce was generally holding