Dubai said on Monday it had started building what would be the world's tallest tower, another record for the city that is already home to the highest skyscraper - the Burj Khalifa.

The Tower at Dubai Creek Harbour - a joint venture between Emaar Properties and Dubai Holding, the investment vehicle of the emirate's ruler, Sheikh Mohammed bin Rashid al-Maktoum - will be completed in 2020, Dubai's government said.

Its statement did not say how high the tower would be nor how much it might cost.

Guinness World Records defines a tower as a structure in which less than 50 percent of the total height is useable floor space.

The world's tallest tower is the Tokyo Sky Tree, a 634-metre-high broadcasting, restaurant and observation tower.

Dubai, a major tourism and entertainment center, is continually laying plans for new attractions.

Its new tower, part of a plush new residential area next to a waterfront, will feature several garden-themed observation decks, it said.

The Burj Khalifa is 829.8 meters (2,722 feet) high.