Sydney  - Danish architect Joern Utzon was a creative genius who gave Australia and the world a great gift when he designed the Sydney Opera House, the custodian of the much-loved waterfront building said Sunday.

Utzon died in his sleep in Denmark on Saturday, aged 90.

Opera House Trust chairman Kim Williams said the lights that pick out the famous sails would be extinguished for an hour on Sunday night as a mark of respect. On Monday, the flags on the nearby Sydney Harbour Bridge were to be lowered to half-mast.

"It has become the most globally recognized symbol of our country," Williams said.

Utzon, who drew up the plans for the Opera House in 1957, stormed off the building site seven years before it was finished and never returned to see it completed.

In 2003, Utzon was awarded the Pritzker Architecture Prize, sometimes called the Nobel prize for architecture.

"We pay tribute to a visionary architect whose design for the Sydney Opera House, an architectural masterpiece, has come to symbolize the spirit of our great nation around the world," New South Wales Premier Nathan Rees said in a statement.

"We are deeply saddened by the death of Joern Utzon, to whom Australia is indebted for its iconic building. Our thoughts and sympathies are with Joern Utzon's family."

More than 7.5 million people visit the famous building every year. (dpa)