VIENNA (Reuters) - The Austrian ski resort of Ischgl and its surroundings are the source of the country’s biggest cluster of coronavirus cases, involving more than 600 infections and possibly twice as many abroad, a public health official confirmed on Thursday.

Hundreds of tourists from countries including Germany, Norway and Iceland are believed to have been infected at the resort, which is near the point where Austria, Switzerland and Italy meet and renowned for its party scene.

The local authorities have been widely accused of responding too slowly as it is now clear the virus found a breeding ground in crowded apres-ski bars at various resorts and spread in Ischgl for a month before it was quarantined on March 13.

“In terms of size, Ischgl is certainly dominant,” the Austrian Agency for Health and Food Safety’s (AGES) head of public health, Franz Allerberger, told a news conference.

“It is not just about these more than 600 people in Austria who are proven to have been infected there. We also have the same number, if not twice that, who are now abroad and whose cases are slowly being reported.”

The 611 cases across Austria are just a fraction of the 10,927 cases Austria has reported, but Ischgl has become a byword for a bungled response to a public health emergency. Officials in Vienna and the provincial capital Innsbruck acknowledge mistakes were made.

For weeks an apres-ski bar called Kitzloch, where a barman and several tourists were infected, is thought to have been the centre of the outbreak. The bar was ordered closed on March 9.

That barman was the first case in the area to be diagnosed because he was the first to go to a doctor, Allerberger said. The barman first showed symptoms on March 2 and his positive test was reported on March 7.

It is now clear that others had the virus well before then. Allerberger told the news conference that “patient zero” was a Swiss waitress at Kitzloch who brought the illness in from Switzerland and first had symptoms on Feb. 5.

Adding to the confusion about the Ischgl outbreak, however, AGES corrected his statement hours later to say it was actually an Austrian waitress at Kitzloch, who first had symptoms on Feb. 8. The Swiss waitress was infected a month later, the agency said in a written statement issued on Wednesday evening.

Following a German media report that an unspecified Ischgl bar or restaurant’s employee tested positive in late February but the case was not reported to authorities, prosecutors have asked the police to investigate whether there was a failure to report an illness.

Ischgl’s mayor, Werner Kurz, said he found out the outbreak there started in early February from Thursday’s news conference.

“We also weren’t aware of the (Swiss) waitress mentioned by AGES until now,” he said in a statement. He and the provincial government separately repeated that the first case came to light on March 7.