KIEV (AFP) - Hundreds of people have fled Crimea and the situation could deteriorate further as tensions continue to rise on the Russian-controlled peninsula, Ukraine's national security chief warned on Wednesday.

"Today there are hundreds of them, but if separatists continue their activities in the Crimea, the number of refugees may increase," National Security and Defence Council Secretary Andriy Parubiy told reporters.

"Ukraine is ready to... ensure the protection of refugees," he added.

"We have taken concrete steps so that we can welcome these refugees and place them in the most comfortable locations."

In total, close to 560 people have fled Crimea in the last few days, with almost 400 arriving on the mainland, Ukraine's border guards service said.

On Wednesday alone, 158 people left the disputed Black Sea peninsula, primarily members of the Muslim Tatar minority, who have traditionally been staunch supporters of Ukraine's independence, the service said.

Tensions in Crimea have escalated into the worst East-West crisis since the Cold War, with Russian forces taking control over Ukraine's southern autonomous region.

Crimea is due to vote on Sunday in a referendum on whether to join the Russian Federation, in a move branded illegitimate by Kiev's new pro-European government and Western powers.