Half of all transatlantic flights are expected to be cancelled on Friday due to a cloud of ash spewing from an Icelandic volcano, the intergovernmental Eurocontrol agency said Thursday.

"Regarding transatlantic traffic, we are aware that 50 flights scheduled to take place tomorrow (Friday) morning have already been cancelled, and we anticipate that 50 percent of all flights from North America to Europe will be impacted tomorrow," Eurocontrol said in a statement.

"On average, there are 600 flights a day between Europe and North America," it added.