Scottish sports events will become "effectively spectator-free" as part of a drive to slow the spread of the Omicron variant of the coronavirus, First Minister Nicola Sturgeon said Tuesday.

Sturgeon told the Scottish Parliament that crowds at outdoor public events would be capped at 500 from Dec. 26 for "up to three weeks."

The announcement follows even tougher measures announced in Wales, where all sports events must be held behind closed doors from the same day.

The new rules in Scotland would impact football fixtures over the Christmas and New Year period including the Old Firm derby between Celtic and Rangers on January 2.

However, a scheduled winter break for the Scottish Premiership between January 2 and 26 could be brought forward to minimize the economic cost to clubs.

"In light of today’s announcement regarding supporters attending matches, Celtic can confirm that it has today requested that the SPFL (Scottish Professional Football Leagues) bring forward the scheduled winter break and reschedule the fixtures affected by the regulations announced," the Glasgow giants said in a statement.

"The game owes it to supporters to explore all opportunities to maximize the prospect of all supporters being able to attend matches and support the game they love."

The new rules will also affect the double-header between Glasgow and Edinburgh in the United Rugby Championship.

Indoor standing events will be limited to 100 spectators, indoor seated events to 200, and outdoor events to 500 people.

"This will of course make sports matches, including football, effectively spectator-free over this three-week period," Sturgeon said.

"And it will also mean that large-scale Hogmanay (New Year) celebrations, including those planned here in our capital city (Edinburgh), will not proceed.

"I know how disappointing this will be for those looking forward to these events, and for the organizers of them."

Three Scottish Premiership matches are due to take place on Wednesday without crowd limits.

However, Celtic's visit to St. Mirren is under threat due to a Covid outbreak among the Saints squad.

Livingston manager David Martindale led the call for a circuit breaker last week with the rapid rise in infections set to impact many more clubs.

"I don't believe it's fair for the competition and the product," said Martindale.

- 'Major blow' -

In contrast to the mass postponements in England, all four Scottish Premiership games and Celtic's 2-1 win over Hibernian in the League Cup final did go ahead last weekend.

Cardiff City chief executive Mehmet Dalman described a blanket ban on fans in Wales as a "major blow."

The Bluebirds' Boxing Day fixture against Coventry has already been postponed due to an outbreak of cases in the Cardiff squad.

Welsh economy minister Vaughan Gething confirmed that a £3 million ($3.97 million) spectator sports fund will be available to support those clubs affected by the loss of revenue.

No such restrictions on attendance have yet been put in place in England.

The Premier League and the English Football League announced their intention to continue with the season on Monday despite calls for a firebreaker to quell infection rates.

Six of the 10 Premier League games and 19 of the 36 matches in the EFL were postponed last weekend.

British Prime Minister Boris Johnson said in a brief video message Tuesday that while unable to rule out new restrictions after Christmas, there was currently not "enough evidence to justify any tougher measures before."

However, he added: "If the situation deteriorates we will be ready to take action if needed," noting the situation "remains finely balanced."

After nearly a full season shut behind closed doors, Premier League clubs have been able to enjoy full crowds since the start of the 2021/22 campaign in August.