STOCKHOLM (Reuters) - Sweden put its top military staff on higher alert on Friday as a result of the situation in Ukraine, the armed forces said.

It is already participating in international maneuvers in Finland, which borders Russia, and has moved its quick-response fighter jets to the island of Gotland in the Baltic Sea, off Sweden's southeast coast.

"Given the serious nature of the development in Ukraine, the Swedish military is responding by among other things a higher alert status for the General Staff at headquarters and intensified intelligence gathering," Forsvarsmakten, Sweden's military authority, said in a statement.

A spokesman for the military declined to give any more details of what Sweden was doing to prepare for any eventual spillover in the region from the conflict.

The past 72 hours have seen pro-Russian rebels suddenly open a new front and push Ukrainian troops out of a key town. Kiev and Western countries say the reversal was the result of the arrival of armored columns of Russian troops. Moscow publicly denies its forces are fighting to support pro-Russian rebels.

(Reporting by Simon Johnson; Editing by Alison Williams)