CATANIA, Italy — Catania airport extended its airspace closure until at least 6 p.m. (1600 GMT) Wednesday, disrupting travel for thousands during the peak summer holiday season after an earlier restriction had been set to expire at 11 a.m.

Europe's most active volcano, Mount Etna, has been spewing large quantities of ash and glowing rock fragments since last Friday, with activity intensifying over the past several days.

Italy's National Institute of Geophysics and Volcanology (INGV) reported thick lava flows emerging from two main vents at altitudes of 2,360 meters and 2,750 meters. Two additional lava flows have since formed, adding to the volcanic output.

Flight operations at Catania airport have faced disruptions since Friday. The airspace corresponding to the ash cloud was fully closed only in recent days, affecting incoming and outgoing flights.

Airport operator SAC confirmed the extended closure, saying the airspace was shut "due to Etna's eruptive activity and the associated release of volcanic ash into the atmosphere."

The closure targets the southwestern air corridor known as sector C1, which lies directly in the path of the ash cloud.

Thousands of travelers are attempting to find alternative routes off the island, including through Palermo's airport or overland by train.

Further decisions on reopening will depend on the stability of Etna's eruptive activity and a reduction in atmospheric ash levels, INGV said.