The event is due to take place in Nairobi between August 17 and 22 having been rearranged following its postponement last year. 

Kenya is on the United Kingdom Government’s list of "red countries" which they warn are at the highest risk from COVID, and should not be visited "except in the most extreme of circumstances."

"This decision has been reached for a number of reasons including UK Government guidance not to travel to red list countries, the associated risks with COVID-19 variants, the significant cost and time required in quarantine both in Kenya and UK, but most importantly the wellbeing of our athletes, coaches and support team," UK Athletics said in a statement.

Kenya has so far recorded more than 174,000 coronavirus cases with 3,378 deaths.

Kenya was awarded the event by World Athletics after it successfully staged the International Association of Athletics Federations - as the world governing body was then called - World U18 Championships.

Britain were among several countries that missed that event after withdrawing due to security concerns.

Britain were part of a group that included Australia, Canada, New Zealand, Switzerland and the United States who withdrew from that event following warnings about the increased threat of terrorism.

The World Athletics U20 Championships have proved a fertile breeding ground for some of Britain’s stars of the future.

Gold medallists at the event have included Colin Jackson in the 110 metres hurdles and Mark Lewis-Francis in the 100m.

Christian Malcolm, the current head coach of British Athletics Olympic Programme, won the 100m and 200m at the 1998 edition of the Championships in Annecy.