Russia's aviation watchdog said on Thursday all four Moscow airports had resumed work after the lifting of temporary restrictions that were introduced to ensure the safety of civil aircraft flights.

All four of Moscow's airports including another about 100 miles southwest of the Russian capital were temporarily shut down for undisclosed security concerns, authorities said.

"To ensure the safety of civil aircraft flights, temporary restrictions have been introduced on the operation of Sheremetyevo, Domodedovo, Vnukovo, Zhukovsky and Kaluga airports," Rosaviatsiya said on Dec.