The airport authority at Sofia International reports that some flights are delayed Thursday over the new heavy snow that hit the capital.

Runways are being cleaned round-the-clock and are closed for cleaning for about 30 minutes after each departing and landing aircraft.

Flights of the national carrier "Bulgaria Air" to Madrid, Rome, Amsterdam and Berlin are all delayed.

The City Hall's services have cleaned several times already the main roads and those used by public transportation, which is running with delays. Huge traffic jams occured in the capital in the early hours Thursday

Meanwhile, it was reported that the Danube River's freezing over is expanding, obstructing navigation even further.

The floating ice has reached Thursday 30% and 50% of the river's surface at the Bulgarian Danube cities of Ruse and Silistra respectively.

The banks and port facilities in both cities are also reported to be sheathed with ice. Vessels and pontoons continue to be hauled aground due to the freezing.

Thursday morning, 15.6 degrees C were measured at Ruse, another record low for this date - the lowest in the last 50 years.