London's marathon is now due to take place on Sunday October 4 instead of its original date of April 26, with Boston postponed until September 14 after previously being scheduled for April 20. 

Marathon world record holder Eliud Kipchoge of Kenya was set to go head-to-head with Ethiopia's distance running legend Kenenisa Bekele in London next month, with doubts now over an appearance later in the year.

"The world is in an unprecedented situation grappling with a global pandemic of COVID-19 and public health is everyone’s priority," London Marathon event director Hugh Brasher said.

"We know how disappointing this news will be for so many - the runners who have trained for many months, the thousands of charities for which they are raising funds and the millions who watch the race every year."

All runners with a place in this year's event will be given a space for the rescheduled October date, with those unable to compete receiving a refund.

Runners can also defer their entry to next year's event, but will need to pay the entry fee again.

UK Athletics are currently looking to host their qualification event for the marathon at this year's Olympic Games in Tokyo on a date between April 25 and 27 in a closed location with limited numbers following the postponement.

Boston is home to one of the most prestigious marathons in the world and is also the oldest, running uninterrupted since 1897.

Boston Mayor Marty Walsh said the race brings more than $200 million (£162 million/€180 million) to the city.

"You think about the economic impact on the city but the bottom line is my job as Mayor is to make sure that people are safe," he said.

There are more than 140,000 people who have been infected by COVID-19, with 1,873 coming from the United States and 798 from the United Kingdom. 

A total of 5,375 people have been killed by the virus, which has spread to over 130 countries and has wreaked havoc on the international sports calendar.