The latest decision to impose the no-fly zone over Britain and Ireland prompted fierce criticism from Richard Branson.
The Virgin Atlantic boss slammed the latest closure of airspace over Britain and Ireland as "beyond a joke".
"All the test flights by airlines, aircraft and engine manufacturers have shown no evidence that airlines could not continue to fly completely safely," the entrepreneur said.
"It is obviously dangerous to fly through the mouth of a volcano, however the volcano is hundreds of miles away.
"Over a thousand flights took off from France last week in similar conditions to that which exist today without encountering any problems or showing any levels of ash concentration.
"We need strong leadership to intervene to avoid doing further unnecessary damage to the economy and lives of travellers."
Britain's two biggest airports suffered major flight disruption today, and a string of others were closed. A no-fly order saw Heathrow and Gatwick shut until 7am today, before only partially reopening.
Flights are also grounded across much of Scotland and Wales and northern England.
A spokesman for British Airways also said airlines should take the decision whether or not it was safe to fly, describing the current approach as "overly restrictive" and "not justified".
"The approach the airspace authorities have taken in relation to volcanic ash remains overly restrictive and not justified on safety grounds.
"The airline industry has a great deal of experience in dealing safely with the potential risk posed by volcanic ash.
"We believe airlines are best placed to take the final decisions on whether or not it is safe to fly. Safety will always be our overriding priority."