The UN High Commissioner for Refugees (UNHCR) Tuesday said the number of people displaced inside Ukraine has doubled in the past three weeks since the ongoing fighting in eastern Ukraine is driving more people from their homes.

As of Sep. 1, UNHCR estimated that 260,000 people were displaced in Ukraine, compared to 117,000 in the first week of August, Xinhua reported.

The UN refugee agency said the displaced are from eastern Ukraine and are remaining in the Donetsk, Kharkiv and Kiev regions.

The actual number of displaced people is even higher as many are staying with families and friends and choose not to register with the authorities, it added.

"The number of those using the three corridors set-up by the Ukrainian authorities to flee conflict areas is decreasing, mainly due to recent incidents when civilians have lost their lives in attacks. Reportedly 6,000 people have left through these corridors since the end of July," Adrian Edwards, UNHCR spokesperson told a press conference.

Meanwhile, the number of Ukrainians is seeking refugee status or asylum in the Russian Federation increased by almost 66,000 during August.

UN High Commissioner for Refugees Antonio Guterres said the steep rise in the number of displaced over the past three weeks was a deep concern.

"If this crisis is not quickly stopped, it will have not only devastating humanitarian consequences but it also has the potential to destabilize the whole region. After the lessons of the Balkans, it is hard to believe a conflict of these proportions could unfold in the European continent," he said.