DUBAI, United Arab Emirates — The Burj Khalifa's owner said today the observation deck of the world's tallest tower has been unexpectedly shut down, disappointing visitors and marring the spire's reputation a month after it opened.

Dubai had hoped the 2,717-foot skyscraper would be a major tourist draw. The Middle East city-state has promoted itself worldwide by wowing visitors with over-the-top attractions such as the Burj, which juts like a silvery needle out of the desert and can be seen from miles around.

In recent weeks, thousands of tourists have lined up for the chance to buy advance tickets for viewing times often days later that cost more than $27 apiece. Now many of those would-be visitors must get back in line for refunds.

The precise cause of the $1.5 billion Dubai skyscraper's closure remained unclear.

In a brief statement responding to questions, building owner Emaar Properties blamed the closure on "unexpected high traffic," but then suggested electrical problems also were at fault.

Dubai opened the tower on January 4. The observation deck is on the 124th floor.