* Crowds barred from much of Australian Open
* Fresh cluster linked to quarantine hotel
* New infections linked to highly contagious UK variant
* Latest lockdown a 'bitter disappointment' - Business Council (Adds comment from tennis players in para 9-12)
By Swati Pandey
SYDNEY, Feb 12 (Reuters) - Australia's second-most populous city will enter a five-day snap coronavirus lockdown, authorities said on Friday, banning spectators for much of the Australian Open tennis tournament.
A fresh COVID-19 cluster linked to a quarantine hotel in Melbourne, the capital of Victoria state, reached 13 cases as of Thursday midnight, as authorities rushed to quash the spread of the virus. All of those infections were linked to the highly contagious UK variant.
Victoria Premier Daniel Andrews announced the lockdown for the state, starting at midnight on Friday, calling it a "short, sharp circuit breaker" banning public gatherings, home auctions, weddings and religious gatherings.
"We must assume that there are further cases in the community than we have positive results for, and that it is moving at a velocity that has not been seen anywhere in our country over the course of these last 12 months," Andrews told reporters, noting the high transmission rate of the UK variant.
Asked about the Australian Open, which runs through Feb. 21, the premier said the Grand Slam tournament, one the biggest events in the country's sports calendar, was considered a workplace, subject to lockdown restrictions.
"There are no fans. There are no crowds. These people are essentially at their workplace," he said.
Tennis fans will be able to attend games scheduled for Friday, while those who had bought tickets to restricted events will get a refund. Williams (NYSE:WMB), who was out on court winning her third round match when the announcement was made, said she would miss the fans.
"It's not ideal," the 23-times Grand Slam champion said. "It's been really fun to have the crowd back, especially here."
Three-time Grand Slam champion Naomi Osaka said she found it "funny" that tennis players were deemed essential workers.
"But I don't know, I don't make the rules. I'm just here just trying to - I don't know, just having fun."
'BITTER DISAPPOINTMENT'
Victoria suspended international passenger flights from Saturday, excluding those already in transit, until further notice.
"We will continue to assess the impact of the UK strain of the virus on our programme and international arrivals, and will provide more information on the duration of this pause soon," the state government said in a statement.
All states and territories, except New South Wales - which includes Sydney and is the nation's most populous state - closed their borders to Victoria on Friday citing the high risk of transmission.
New South Wales, which on Friday recorded a 26th day with no community cases, said its borders with Victoria would remain open while it monitors the situation.
Victoria endured one of the world's strictest and longest lockdowns last year after an outbreak that killed more than 800 in the state, the vast majority of the national death toll.
The head of Australia's business lobby group expressed frustration at the fresh lockdown, calling it a "bitter disappointment for the whole community".
"This is the second lockdown caused by Victoria's hotel quarantine system, it must not be as long and destructive as the last," Business Council Chief Executive Jennifer Westacott said. "We must get hotel quarantine working properly."
More broadly, Australia has been among the world's most successful countries in handling the pandemic, largely because of decisive lockdowns and borders sealed to all but a trickle of travellers. The nation has recorded some 22,200 community cases and 909 deaths. its quarantine hotels, where all international arrivals have to spend two weeks, have been a weak link in its defences, with the latest Melbourne cluster another example.
Premier Andrews proposed tightening Australia's citizen repatriation program to compassionate reasons only, a move that could get some support from other states that have had the UK strain.
Ahead of the lockdown announcement, Prime Minister Scott Morrison offered his government's full support for Victoria's decisions on containing the outbreak.