Copenhagen - US hip hop star Kanye West was the top act Thursday on the opening day of the annual Roskilde music festival, near the Danish capital Copenhagen, with some 65,000 visitors enjoying the festivities under blue skies.

The lineup during the four-day festival that ends Sunday includes Coldplay, Pet Shop Boys, Nick Cave, Oasis, Slipknot, Nine Inch Nails and some 150 other acts.

Organizers said US hip hopper Lil Wayne had been forced to cancel his appearance on Saturday "due to doctor-mandated rest."

The music festival also conducts fund-raising, generating funds mainly through bottle deposits.

Efforts to tackle climate change was a theme for the 2009 festival, not the least since Denmark is in December to host a United Nations conference where countries will seek to agree on a new treaty to succeed the Kyoto Protocol on reducing greenhouse gas emissions.

Visitors to the festival were invited to take "10 green footsteps" including using public transport, riding a bike to the festival, recycling garbage, and switching off electric appliances instead of letting them remain on standby.

The Danish relief agency DanChurchAid was to channel funds raised to help victims of climate change in Bangladesh and India.

In 2008, the bottle deposits generated some 189,000 dollars.

The first Roskilde festival was held in 1971, inspired by similar events at Woodstock and the Isle of Wight.

More details are available online at www. roskilde-festival. dk. (dpa)