Budapest is among around three cities that have supposedly expressed serious interest.

The Hungarian capital is still considered the favourite at this stage.

As part of a new and more informal process for selecting host cities, the IAAF have not undergone any structured bidding process for their showpiece event and do not plan to announce official candidates.

They hope to be in a position where one city will be proposed at the Council meeting in Buenos Aires on July 26 and 27.

If this idea is approved by the Council, the choice will be publicly announced.

The chosen city would not, however, be formally approved as host until later this year, with another Council meeting in November currently considered the most likely timeframe for a final decision.

Barcelona is another city that has been rumoured to be interested.

It is possible that some contenders will not get the nod for the World Championships but could be recommended for other IAAF events.

Doha in Qatar is due to host the 2019 IAAF World Championships before Eugene in United States follows suit in 2021.

This will mark the first time consecutive editions of the biennial event have been held outside Europe. 

A host in Africa is widely expected to be found for the 2025 edition.