Russia and Germany have called on the OSCE to double the number of observers monitoring a truce in eastern Ukraine to 1,000, according to BBC News.

Russian Foreign Minister Sergei Lavrov and his German counterpart Franck-Walter Steinmeier urged the OSCE to "ramp up" its mission. The group has said it has experienced problems gaining access to key areas.

Meanwhile, Ukrainian government sources told the BBC they believed Russian troops were still entering the country. According to some claims, there could be at least 18,000 involved.

Last month's ceasefire agreement reached in Minsk required all foreign troops to leave the region.