England allrounder Tom Curran has withdrawn from the BBL citing the need to spend some time at home after nearly five months in biosecure bubbles.

The news comes just days after England team-mate Tom Banton also withdrew from the tournament for similar reasons. The pair have been in biosecure bubbles since cricket resumed in July. Both players were part of England's white-ball squads before heading to the IPL and both have been in South Africa where Covid outbreaks have wreaked havoc with the tour.

Depending on the outcome of the tests in the England camp that are currently being ratified there could be further impact on players coming to the BBL. Those in the tournament were due to fly directly from South Africa after the ODIs, but if there are positive tests within the group they may not be able to leave the country straightaway

"I'm really sorry not to be playing in this year's Big Bash," Curran said. "As you'll already know, it's been a very challenging year and I've been in bubbles since July.

"I feel very lucky to play for the Sixers, I have loved my time with you all over the last two seasons and I can promise you, this decision was not taken lightly.

"I will hopefully be back for many years to come, recharged and ready to go again, but for now I just need some time, normality, see family and be home."

Sixers general ganager Jodie Hawkins said: "The varying conditions we are asking our players to play cricket in worldwide is taking its toll and we understand Tom's need for a break over this BBL season. While the hub conditions here are much less restrictive than other tournaments, the constant requirement to lock down has been tough and our number one priority is the welfare of our players."

Covid-19 and Australia's strict quarantine requirements are causing issues for the BBL after the league changed the rules this season to allow three overseas instead of two.

Clubs have gone on a signing spree and the BBL was shaping to feature some high-quality internationals given international cricket was in a state of flux.

Sam Billings, Jason Roy, Liam Livingstone, and Lewis Gregory are due to come from South Africa and need to complete 14 days of strict quarantine prior to being available to play. Dawid Malan arrived over the weekend and is currently quarantining in Perth.

Afghanistan spinner Mujeeb-Ur-Rahman tested positive for Covid-19 while in quarantine in Australia and had to be hospitalised, meaning he will likely miss the early part of the tournament.

Mohammad Nabi and Noor Ahmad had the start of their 14-day quarantine delayed after they were not allowed to fly to Adelaide as originally planned due to a Covid outbreak in the city. As a result, the pair will miss the Melbourne Renegades first two games and the Renegades have signed Gloucestershire allrpunder Benny Howell as a replacement, as he is currently in Victoria with his family. The Renegades are sweating on the availability of Imran Tahir in January as he is not set to arrive in Australia until after Christmas.

The Hurricanes are confident Sandeep Lamichhane will be available to fly to Australia to play in January despite testing positive for Covid in Nepal.

The Hurricanes have convinced Johan Botha to come out of retirement at age 36 to play as a replacement, after retiring from the BBL to take up coaching.

"I figured I'm as fit as I've ever been, and I feel I can still make a contribution to the team," Botha said. "I've missed playing but I didn't really want to put it out there and say 'can you pick me' in case it didn't work out, so we kept it quiet from when we first chatted about it at the Shield hub in Adelaide, and it slowly built up from there."

"The little Covid cluster in Adelaide for instance didn't help, so we just kept it quiet all along to make sure everything lined up."