Britain's Queen Elizabeth II on Tuesday unveiled a permanent memorial fountain to memorize late Princess Diana in Hyde Park, central London, almost seven years after Diana's death.

Diana's sons Princes William and Harry, her ex-husband Prince Charles and her brother Earl Spencer attended the official opening ceremony of the publicly-funded memorial.

It was the first time Diana's two families have come together since her funeral in London on 1997 after she was killed in a car crash in Paris.

In her speech, the Queen said the days after Diana's death were"etched" on her memory.

"By any standard, Diana's tragic death held the attention of the world," she said.

"Central to this remains the extraordinary effect Diana had on those around her," she said.

"I cannot forget, and nor can those of us here today who knew her much more personally, as sister, wife, mother, or daughter-in-law, Diana who made such an impact on our lives," said the Queen.

The 700-ton granite fountain, designed and built at a cost to the British taxpayer of 3.6 million pounds (about 6.59 million US dollars), consists of a stone ring 210-meters in circumference.

The fountain's construction has been dogged by delays and bureaucratic wrangling. The Royal Parks finally provided extra funds after the creation ran 600,000 pounds (about 1,080,000 US dollars) over budget.