ST. PETERSBURG, July 29 (Xinhua) -- The Pulkovo airport in Russia's northern capital of St. Petersburg was briefly evacuated Tuesday because of a bomb threat.

A total of nine flights were held back as local bomb squads combed the airport for explosive materials after receiving a call of the bomb threat, the Itar-Tass news agency reported.

The Pulkovo airport, the third busiest airport in Russia, returned to full service two and a half hours later following a full evacuation and no suspicious objects were uncovered.

Meanwhile, Moscow's Domodedovo International Airport also received a similar threat.

Long queues and confusion were reported at the two airports throughout the day as Russian authorities worked to ascertain the degree of threat.