A fourth contracting group has joined the race for the contract to build what would be the world’s tallest building, the 1-kilometre-high Kingdom Tower on the outskirts of Jeddah.

A joint venture of the local El-Seif Engineering & Contracting and Belgium’s Six Construct has joined three contracting groups that were shortlisted by the client, Saudi investment firm Kingdom Holding, in September.

The three shortlisted groups were South Korea’s Samsung Corporation with Dubai-based Arabtec Construction, Australia’s Multiplex and Saudi Binladin Group (MEED 11:9:09).

The bidders had originally expected an award to be made last year but the developer now wants to consider proposals from other contracting groups that may be able to offer a lower price.

Kingdom has shortlisted two architectural firms. They are the Chicago office of Skidmore, Owings & Merrill, which was responsible for the recently opened Burj Khalifa tower in Dubai, and US-based Adrian Smith & Gordon Gill Architecture. An architect is expected to be appointed in February.

US-based architects Pickard Chilton, in partnership with UK-based Hyder Consulting, had also been competing for the role, but has dropped out of the contest.

If the project goes ahead, it will replace Burj Khalifa as the world’s tallest building. The 828-metre-tall building was known as the Burj Dubai until it was officially opened on 4 January, when the new name was revealed.