Upgrades to Yekaterinburg's stadium for the 2018 World Cup will cost $30 million, local authorites said Thursday.

The Ural Mountains hub is one of 11 host cities for the tournament, and its Central Stadium is one of two that is being refurbished rather than built from scratch.

A tender posted on a government website values the improvement work at 950 million rubles. The winning contractor must raise the temporary capacity of the arena to 45,000 seats from the current 27,000.

Project designs released by the bid committee envisage a modern circular roof being constructed on top of the elegant, sloping yellow bowl that currently exists.

The new frame is to support additional stands that will be removed after the World Cup.

The winner will be announced on December 3, and will have three years and four months to complete the work.

Central Stadium was built in 1957 and hosts the Russian Cup final as well as under-21 matches for the Russian national team.