Ukraine said on Sunday its forces regained control of a police station in Luhansk, in what could be a breakthrough in Ukraine's efforts to push back pro-Moscow separatists who controlled the city for months.
Kiyv said its forces raised the national flag over the station, and claimed that the rebels were fighting a desperate rearguard action to hold on to Luhansk, which is their supply route into neighboring Russia.
Meanwhile, a column of armored vehicles led by pro-Russia rebels was reportedly spotted near the Russian border. Heading west, deeper into rebel held territory, it was said to include a mobile surface-to-air missile system.
Earlier, pro-Russian separatists shot down a Ukrainian Mig-29 fighter jet Sunday in the war-torn eastern region of the country.
A military spokesman said the pilot ejected from the plane and was rescued from the Luhansk area.
In related developments, at least 10 civilians were killed in the last day in fighting in the rebel-held city of Donetsk, local authorities reported.
Officials of the International Committee of the Red Cross have arrived in Russia near Ukraine's border to start inspections on a huge Russian aid convoy parked near Ukraine's border.
An ICRC spokeswoman told the news agency that an agreement was reached Saturday on how to inspect the convoy. She said she doubted the inspections would begin Sunday. However, Ukrainian officials said they have begun inspecting the aid convoy.
The nearly 300 truck convoy parked outside the Russian town of Kamensk-Shakhtinsky is awaiting security guarantees to allow it to cross into Ukraine with the humanitarian aid. The ICRC would then have the responsibility for distributing the aid to Ukrainians caught in the conflict between Ukrainian forces and separatists.
Moscow said the mission was purely humanitarian, but Kyiv and the West have voiced concerns it could serve as a "Trojan Horse" for an invasion or a way to re-arm pro-Russian rebels who have suffered previous losses.
The foreign ministers of Russia, Ukraine, France and Germany met Sunday in Berlin to discuss the tensions in Ukraine.
Germany's Frank-Walter Steinmeier said he and his collegues will report back to their leaders and then possibly agree Monday or Tuesday how to continue talks. He added that the group's main objective remains to bring about cease-fire in Ukraine
French President Francois Hollande and European Commission President Jose Manuel Barroso discussed the situation Saturday. Hollande called on Russia to respect Ukraine's territorial integrity and urged Kyiv to exercise restraint in its military activities. He said France was ready for a new summit on the issue and added that Sunday's meeting could be used as a first step toward that end.
Some information for this report was provided by AFP and Reuters.