(Writes through with details, context)

Sept 13 (Reuters) - Nonbinary athletes will be able to compete in next year's Boston Marathon without having to register in either the men's or the women's divisions, organisers for the United States' most popular running event said.

Registration for the April race opened on Monday. The Boston Athletic Association $(BAA)$ said the application allows runners to select nonbinary with regard to gender, making the race the latest nationwide to open such an option.

Nonbinary athletes who have previously completed a marathon as a nonbinary participant will be eligible to submit an application selecting the new option, the BAA said on its website.

"Discussions are ongoing with nonbinary athletes in an effort to further promote inclusion at all BAA events," the group said.

The Boston Marathon regularly features star-studded slates of Olympic medallists from around the world, leading a pack of 30,000 runners from the city's western suburbs to a finish line in its historic Back Bay neighbourhood.

The 2023 race will mark the 10th anniversary of the deadly 2013 Boston Marathon bombings.

Runners hoping to compete in the annual race are required to meet strict qualifying times. The BAA said that because it does not yet have enough data to establish nonbinary qualifying times, it will use standards applied to the women's division.

"As we prepare for future races, participants can expect nonbinary times to be updated accordingly," the BAA said. It was unclear whether the BAA has a policy for applications from transgender runners.

Over 200 races nationwide have added a nonbinary division for participants, according to Jake Fedorowski, a runner who created an online guide to nonbinary inclusion in the field.

Fedorowski's work is sponsored by the Road Runners Club of America and Seattle Frontrunners, two popular running groups.

The Brooklyn Marathon and Half Marathon, another popular running event, had over 80 finishers in the nonbinary division of its April 2022 races, according to its website.

(Reporting by Rami Ayyub in Washington and Aadi Nair; Editing by Peter Rutherford and Toby Davis )

((Aadi.Nair@thomsonreuters.com;))