WASHINGTON — US President Barack Obama cancelled his trip Saturday to attend Polish president Lech Kaczynski's funeral, citing the huge cloud of volcanic ash that has plunged air travel throughout Europe into chaos.

"I spoke with acting President (Bronislaw) Komorowski and told him that I regret that I will not be able to make it to Poland due to the volcanic ash that is disrupting air travel over Europe," Obama said in a White House statement.

"Michelle and I continue to have the Polish people in our thoughts and prayers, and will support them in any way I can as they recover from this terrible tragedy."

Obama, who cancelled his trip hours before departing for Poland aboard Air Force One, said "President Kaczynski was a patriot and close friend and ally of the United States, as were those who died alongside him, and the American people will never forget the lives they led."

Dozens of world leaders including Obama had been due to fly into Krakow for the Sunday funeral of Kaczynski, killed with his wife and 94 other members of Poland's elite in an April 10 air crash in Russia.

But Obama was among a growing number of world leaders, including German President Angela Merkel, Canadian Prime Minister Stephen Harper and Spanish Prime Minister Jose Luis Rodriguez Zapatero, who called in their regrets as the ash crisis evolved into one of the worst air traffic disruptions in history.

The US cancellation followed announcements that several countries in Europe -- including Poland -- closed their airspace in the biggest airspace shutdown since World War II.

The crisis was affecting millions of people around the world and costing airlines hundreds of millions of dollars.

US carriers on Saturday grounded a majority of flights to Europe for a third straight day, cancelling 282 of the 337 scheduled transatlantic flights, according to the Air Transport Association.