Play will not start until 2pm local time at the earliest, the Badminton World Federation (BWF) has said, to allow for the samples to be tested again.

"BWF can also confirm that a small number of positive tests were recorded, and in agreement with Public Health England, these cases will be retested," added the global governing body.

"These cases will continue to self-isolate while they are retested."

The development is a blow for organisers, who were dealt another earlier in the week when Olympic champion Carolina Marín withdrew due to injury.

Marín was due to be the women’s top seed at the event and scheduled to face Thailand’s Supanida Katethong in the opening round.

But the Spaniard pulled out, citing an injury suffered on the way to winning the recent Swiss Open in Basel.

Her withdrawal opens up the top half of the draw for the likes of Japan’s Akane Yamaguchi, Beiwen Zhang of the United States, Thailand’s Pornpawee Chochuwong and India’s PV Sindhu - the current world champion.

Yamaguchi is set to make her first appearance at an international event since competing at last year’s All England Open.

Compatriot Nozomi Okuhara, a bronze medallist at Rio 2016, heads the lower half of the draw and could meet Thailand’s Ratchanok Intanon in the semi-finals.

COVID-19 has been a feature of the build-up to the tournament and English pair Gabby and Chris Adcock had already been forced to pull out due to the long-term effects of coronavirus.

Since contracting the virus at Christmas, Gabby Adcock said she has been unable to train properly and feels "exhausted".

"I don't want to step on court when I'm not conditioned to win," the 30-year-old told the BBC.

"And that's what I want to do, go into tournaments knowing I can win. 

"I still can't smell anything, I'm looking forward to getting this back. 

"I'm just very grateful my health is on the way up."

The Japanese team pulled out of three BWF events in Thailand after men's world number one Kento Momota tested positive for COVID-19 in January, but have travelled to England.

Momota’s return has raised hopes of a showdown with Danish rival and defending champion Viktor Axelsen.

The Japanese star leads the head-to-head 14-1, beating Axelsen in the 2019 All England final, but the duo have yet to meet this year.

Momota has not played an international match since winning the Malaysia Masters in January 2020, largely due to facial injuries sustained afterwards a traffic accident.

With Momota sidelined, Axelsen has been almost unstoppable, becoming the first Dane in two decades to win the men’s singles title at the 2020 All England Open.

Axelsen has won 23 of his last 24 matches, clinching the Yonex Thailand Open, the Toyota Thailand Open and the Swiss Open.

Compatriot Anders Antonsen is also expected to be in contention along with Indonesian duo Anthony Sinisuka Ginting and Jonatan Christie.

The event, scheduled to run from tomorrow until March 21, is also set to feature men’s doubles, women’s doubles and mixed doubles competitions.

Due to the coronavirus pandemic, matches will be held behind closed doors at the Arena Birmingham.