U.K. acts Gary Numan, the Cribs and Bad Lieutenant could miss their Coachella Festival appearances this weekend because of volcanic ash affecting flights.

All flights in and out of Britain have been stopped because of a volcanic eruption in Iceland. The ash has been moving south and has also affected flights in Norway, Sweden, Finland and Denmark, with up to 4,000 planes canceled.

U.K. alt-rock the Cribs, which features former Smiths guitarist Johnny Marr, is stuck in the U.K. and now has little chance of getting a flight from London Heathrow in time for their set on the opening day of the festival (April 16). The band had already boarded a plane when they were informed it had been canceled. Their only hope is getting a slot on a later day.

Synth-pop veteran Numan has posted on his official Web site about the travel problems. He has until April 18 to make it to the festival.

"The last thing I expected this morning when I woke up was to hear that volcanic ash might be preventing us from flying to America," he posted today (April 15). "At the moment the very best British Airways are offering us, and this without any guarantee, is to put us on a Sunday flight that gets in to Los Angeles in the afternoon on Sunday."

However, Numan said even then they only would just make it to the site on time. They would not be able to rehearse with U.S.-based guitarist Robin Finck and would struggle to collect and check all their equipment.

"We are still waiting to find out if British Airways can offer any better alternatives," he wrote. "Very upsetting though to see such a huge opportunity slipping through your fingers. I am glued to the TV news at the moment."

Bad Lieutenant, led by former New Order frontman Bernard Sumner, begins a brief U.S. tour tomorrow (April 16) at San Francisco's Regency Ballroom, followed by an April 17 set at Coachella and then Chicago Park West (April 19) and New York Webster Hall (April 21).

"The members of Bad Lieutenant were scheduled to leave the U.K. today to make their U.S. concert debut, but due to the volcanic eruption in Iceland closing British air space, their flight was canceled," said a statement. "They are scheduled for a flight tomorrow morning - pending airspace restrictions being lifted by the British government - that will put them into San Francisco in time for tomorrow night's concert. At this point, all four of their U.S. dates, including Saturday's performance at the Coachella festival, are expected to take place."

Other acts were more fortunate as they were already on tour in the U.S., including Florence and the Machine, Muse and the xx. Hot Chip, Sweden's Fever Ray and Echo and the Bunnymen did make flights before the disruption, and Thom York and Gorillaz were already in the U.S.