Members of British music group Coldplay, from left, Will Champion, Guy Berryman, Chris Martin and Jon Buckland attend a news conference Mexico City, Sunday, March 4, 2007. (AP Photo/Marco Ugarte)

MEXICO CITY - Coldplay lead singer Chris Martin said Sunday his band is working on a new album featuring what he called a quintessential song that everybody should hear "before we die."

Martin and his band spoke hours before the final concert of a Latin American tour that took them to Chile, Argentina, Brazil and Mexico.

The band said it plans to return to the studio after a two-year hiatus to record an album that will have a different sound from "X&Y," which has sold more than 2 million copies since it was released in 2005.

"I think for a long time people felt like we were a band in black-and-white, and now we feel like because we have this incredible job, now we can do whatever we like and try all kinds of new things," Martin said.

He added that the record will include what could be Coldplay's best song yet.

"In order for us to get excited about a new album, we have to have one song that we feel like everybody has to hear ... before we die, otherwise we'll be terribly depressed," Martin said. "So luckily with this new record we're going to make, we have that one song."

"I can't tell you about it, but it's basically genius," he joked.

Martin, who celebrated his 30th birthday on a Mexican beach last week, also said he is proud of Coldplay's activism to raise awareness about free trade practices around the globe and support poor farmers in developing countries.

Martin is a spokesman for the British aid group Oxfam's "Make Trade Fair" campaign, and Oxfam volunteers provide information on free trade and distribute petitions at Coldplay's concerts.

The singer said he has hope for the future with less than two years left in President Bush's term. "I think we're all excited, everyone in the world is excited about the American elections next year," he said. "Sometimes it's easy to give up all hope."