Flights from Sydney to Europe resumed Wednesday after almost five days of grounding which stranded millions of passengers and caused hundreds of millions of dollars in lost revenues after a massive eruption of a volcano in Iceland prevented flights from and into Europe.

However, Australia's largest carrier, Qantas, said its planes would remain grounded despite the opening of London's Heathrow airport.

Singapore Airlines flight SQ222 will be the first flight out of Sydney Airport to northern Europe at 3:25 Wednesday and is expected to arrive to its destination at 9:55pm Singapore time. Flights to Sydney to Europe resumed after the European air space reopened Wednesday.

However, Qantas planes from other Asian airports will resume their flights to Frankfurt and London on Wednesday evening following the reopening of the European airspaces.

Qantas flights bound for Frankfurt and London will depart from Asian airports on Wednesday evening following the reopening of European airspace.

Qantas chief executive Alan Joyce said full service between Australia and Europe via Asia would restart on Thursday.

He said in a statement, "Qantas welcomes the opening of airspace and we will resume flights out of the UK to Australia today and from Asia to London and Frankfurt. We have been closely monitoring the evolving situation in Europe and liaising with European authorities about the opening of airspace across Europe."

However, Joyce predicted it would take between two and three weeks to clear the airlines from the backlog of passengers created by the disruption of flights into Europe following the eruption of a volcano in Iceland. Millions of passengers across the globe have been stranded because of the closure of the European airspace.