STOCKHOLM — A large earthquake hit Iceland's Bardarbunga volcano system early on Saturday, but there was no sign of a fresh eruption, the country's Meteorological Office said.

Authorities have been on alert since a surge of small quakes there this month triggered memories of the 2010 eruption of the Eyjafjallajokull volcano, which spewed out ash and shut down much of Europe's airspace.

A magnitude 5.4 quake was recorded under Bardarbunga's main volcano at 0703 GMT, said Icelandic Met Office seismologist Martin Hensch.

It came a day after a small eruption in a fissure in a glacier about 40km (25 miles) from the main crater in Iceland's largest volcano system.

The Met office initially raised its aviation warning to red, its highest level, on Friday, then reduced it to orange and removed all airspace restrictions after the eruption stopped.

Hensch said there were currently no signs of magma heading back to the surface, though it was impossible to predict how the situation would develop.

"There are so many parameters in this system," he said. "We cannot make a forecast for the next hours or the next few days. So we have to continue to monitor and react to events when they happen."