KIEV, May 21 (Xinhua) -- The Organization for Security and Cooperation in Europe (OSCE) said on Monday that the situation in the conflict-hit eastern Ukraine has significantly escalated in the past week.

"Last week was in many ways the worst we have seen so far this year. In total, we recorded almost 7,700 cease-fire violations," Alexander Hug, deputy chief monitor of the OSCE special monitoring mission to Ukraine, told reporters in Kiev.

The violence, which included the use of the heavy artillery, has resulted in civilian casualties, Hug said, noting that the OSCE monitors have confirmed two deaths and three injuries among the non-combatants last week.

The mission's observers are currently verifying the reports of four fatalities and six injuries, Hug said.

The conflict in eastern Ukraine has started in April 2014 after the government army launched offensives to regain control over the cities and towns seized by armed groups, who declared independence.

According to the latest United Nations estimates, over 2,500 civilians were killed, and about 9,000 others injured since the start of the violence.

In the past two years, the number of conflict-related civilian casualties has significantly decreased.