* Kiev leaders worried about events in Crimea
* Peninsula is home to Russia's Black Sea fleet (Adds quotes, details)
KIEV, Feb 25 (Reuters) - Ukraine's acting president and security chiefs expressed concern on Tuesday about "signs of separatism" and threats to the country's territorial integrity in mainly Russian-speaking Crimea.
Oleksander Turchinov summoned the "power ministries and agencies" to discuss Crimea after protests on the southern peninsula against the leaders who have taken charge in Kiev following the ousting of President Viktor Yanukovich.
A Russian-speaking mayor has been appointed in Sevastopol, the Crimean port city where Russia's Black Sea fleet is based, and Russian speakers have staged rallies in the region to show hostility to the new authorities in the national capital.
"During the meeting, we discussed the question of not allowing any signs of separatism and threats to Ukraine's territorial integrity (meaning the events which have taken place in Crimea) and punishing people guilty of this," Turchinov's press service said in a written statement.
It gave no other details. Such meetings have in the past usually grouped defence and interior ministry officials, law enforcement bodies and the intelligence services.
Some people in Crimea call openly for moves to secede from Ukraine. The peninsula used to be Russian territory but was transferred in 1954 to Ukraine, which like Russia was then part of the Soviet Union.
Most of Crimea's population speak Russian and the region has close ties with Russia. Some Russian speakers have started forming militias in a show of strength that underlines their dissatisfaction with the political changes in Kiev.
Urging Russia not to meddle in Crimea, Arseny Yatsenyuk, a senior parliamentarian in Kiev, said: "The situation in Sevastopol is very complicated. We appeal to our Russian partners to recognise its responsibilities."
Russian media and officials have portrayed the new leaders in Kiev as nationalists who have seized power and have expressed concern about the situation, but the Kremlin and the government in Moscow have not responded to calls to intervene.
(Reporting By Timothy Heritage)