US President Barack Obama on Monday paid tribute to Richard Holbrooke, the veteran US diplomat whom he called "a true giant of American foreign policy".

Obama issued a statement shortly after news of the death from a heart ailment of the 69-year-old Holbrooke, who was currently a special envoy for Afghanistan and Pakistan.

In a career spanning five decades Holbrooke is said to have worked hard to resolve some of the world's toughest conflicts.

Obama had tapped Holbrooke as his special envoy to Afghanistan and Pakistan shortly after his January 2009 inauguration, tasking him with one of the most difficult diplomatic dossiers confronting the United States today.

Holbrooke's death comes at a critical time with the US administration due to unveil in the coming days a key review of its troop surge in Afghanistan and campaign against the Taliban on both sides of the Afghan-Pakistan border.

A hard-nosed trouble shooter, Holbrooke is perhaps best known for brokering the 1995 Dayton peace accords managing to hammer out a treaty which many privately thought would be impossible.

"Michelle and I are deeply saddened by the passing of Richard Holbrooke, a true giant of American foreign policy who has made America stronger, safer, and more respected," Obama said.

"He was a truly unique figure who will be remembered for his tireless diplomacy, love of country, and pursuit of peace. For nearly 50 years, Richard served the country he loved with honor and distinction."

Holbrooke's career began during the Vietnam war, he moreover served as an assistant secretary of state and US ambassador to Germany and later to the United Nations.

"I expressed to them the gratitude of the American people for his lifetime of service," Obama said.

"They are in our thoughts and prayers tonight. Tonight, there are millions of people around the world whose lives have been saved and enriched by his work.

As I said earlier this evening, the United States is safer and the world is more secure because of the half century of patriotic service of Ambassador Richard Holbrooke."