Glastonbury Festival organizers have taken the unprecedented step of re-starting the ticket-registration process, after tickets for the famous June 27-29 music event failed to sell out in typically-rapid fashion.

Registration will re-open this afternoon, allowing the public to apply for the 40,000 tickets which remain available.

"We had 225,000 people re-register back in February. But from that only 100,000 have bought tickets since Sunday morning, which is quite remarkable. I don't know why," Glastonbury founder and organizer Michael Eavis tells

The registration process, which requires festival-goers to submit basic personal details and a photo, was established in 2007 as part of an effort to squeeze out ticket scalpers. The entire allocation of 137,500 tickets sold out last year in about 2 hours. This time, however, just 100,000 tickets have changed hands in about 48 hours since going on sale.

"At 4pm today," says Eavis, "we've got to come back with a plan I devised yesterday, to catch a new crop of people who want to come and who haven't pre-registered. There'll be quite a crowd of people who get on board today."

Observers are blaming sluggish sales on a mixture of the bad weather which has mired previous events, competition from other festivals, and Jay-Z's booking as a headline performer. Eavis dismissed published reports that Jay-Z was on the verge of pulling out of the fest. "The Jay-Z thing is definitely on," he says. "We got all the production stuff for Jay-Z's show this morning."

However, "two years of bad weather on the trot is taking its toll," admits Eavis. "There's some truth in that."

A spokesman for Glastonbury plays down those factors, and says the organizers are crossing-fingers to break the weather hoodoo, which has seen the Worth Farm site transform into a mud bath in successive editions.

"Many reasons have been given for why tickets sales have been slower this year, the bad weather of the past three festivals probably being highest on the list," the spokesperson says. "We're hoping this year will break the run and burst out in brilliant sunshine."

On the Jay-Z front, the spokesman says, "We like to be adventurous at Glastonbury, hence Jay-Z, but he's only one of 1,000 music performances which span every genre you can imagine. The festival is so much more than just one act."