Paula Radcliffe has waded into a row over the entry requirements for transgender athletes at one of the world’s most elite marathons, suggesting it is “unfair” on women.

Next week around 30,000 runners will line up to compete at the 2019 Boston Marathon after securing a place by hitting the qualifying time for their age and gender category.

For men aged between 18 and 34, a Boston bib has to be earned with a speedy time of 3hrs 5mins or quicker at the 26.2-mile marathon distance in an official race.

Women of the same age, meanwhile, need to beat a target which is half an hour slower - at 3hrs and 35mins.

However, in a shake-up of entry rules, the Boston Athletic Association officially confirmed before last year’s event that transgender runners could compete in the Marathon Major as the gender with which they identify.

It meant several runners who identified as female secured places, despite not having times quick enough to have qualified in the male categories.

The announcement sparked a debate about whether transgender runners were getting easier access to the race due to an unfair biological advantage.

Radcliffe, who is Britain’s most celebrated female distance runner and still holds the world record for the fastest women’s marathon, hit out at the rules.