Last updated on .From the section Formula 1

Korea hosted a Formula 1 grand prix between 2010 and 2013

The Korean Grand Prix has been dropped from the 2015 calendar, reducing the season to 20 races.

The race was a surprise addition to the schedule last month but the FIA said on Tuesday that it had now been omitted from the final version of the calendar.

A spokesman said Korea had been added at commercial rights holder Bernie Ecclestone's request and removed when it became clear it was not viable.

The revised schedule has been published on the FIA's official website. external-link

The decision is not a surprise.

It had been scheduled as the fifth race of the season on 3 May, just a week before the first European race in Spain, but sources had always insisted its inclusion was a ruse.

It was added as a potential way to allow the engine manufacturers to continue to use five engines this season, rather than the four demanded in the 2015 rules.

This plan was based on a rule that says each driver could have five engines in 2015 if the calendar had more than 20 races "as originally scheduled".

Top-level sources said the move came after pressure from, particularly, Renault and its works team Red Bull.

Renault struggled with reliability last year and is under pressure to improve its engine to try to catch up with the dominant unit from Mercedes.

But rival teams pointed out that the calendar published in December - which featured Korea but labelled it unconfirmed - was not the original schedule as a previous version, without Korea, had already been published in September.

And the pressure to allow drivers to use five engines over the season was reduced by the decision to allow limited in-season engine development, after Ferrari pointed out a loophole in the rules.