US President George Bush has postponed a scheduled statement promoting a federal advertising campaign on the dangers of prescription drug abuse.

White House press secretary Dana Perino confirmed that the decision was taken in light of the death of actor Heath Ledger.

It is still unclear what caused the death of the 28-year-old Brokeback Mountain star, but prescription drugs are suspected to have played a role.

“We thought it would be better to postpone the event rather than run the risk of anyone thinking that we were being opportunistic in highlighting the issue,” Ms Perino said, reports AP.

Ledger, who was nominated for an Oscar for his performance as Ennis del Mar in Brokeback Mountain, was found dead in his apartment in New York on Tuesday.

Police have said that no illegal drugs were found on the premises, but they did discover six different types of prescription medications, ranging from an antihistamine to insomnia and anxiety drugs, ABC News reports.

Ledger’s housekeeper said he was alive, asleep and snoring at 1pm on Tuesday but when she returned to his bedroom at 2.45pm he was unconscious.

Her first call was to actress Mary-Kate Olsen, who responded by sending her security people to the house. The housekeeper then called the emergency services.

Paramedics declared him dead at the scene.

Brokeback Mountain director Ang Lee paid tribute to the star yesterday.

“Working with Heath was one of the purest joys of my life,” he said.

“He brought to the role of Ennis more than any of us could have imagined, a thirst for life, for love and for truth, and a vulnerability that made everyone who knew him love him. His death is heartbreaking.”