A clean-up operation has got underway after hundreds of people gathered in Cardiff Bay on Friday.
Huge crowds were seen drinking and playing music outside the Senedd - despite Covid restrictions only allowing six people from two households to meet outside while maintaining social distancing.
Cardiff Council said a number of rules were broken in the "illegal" gathering.
Teams have been cleaning up large amounts of bottles, beer crates, food wrappers and plastic bags left behind since the early hours of Saturday morning.
Industrial bins were installed in the area earlier this week, after litter was left behind following another gathering, but they were empty according to the council.
ITV Wales Reporter Mike Griffiths' footage of the scene on Friday evening
A Cardiff Council spokesperson said: "Once again our teams have been faced with the huge task of cleaning up a significant amount of rubbish left behind by large groups of people intent on breaking Covid-19 restrictions.
"Despite the preventative measures put in place by the council, in partnership with South Wales Police, the Welsh Government’s coronavirus regulations were again broken by a significant number of people illegally gathering in Cardiff Bay.
"The rules are clear, six people, from two households are allowed to meet outdoors, maintaining 2 metre social distancing. Breaking these rules significantly increases the chances of Covid-19 cases rising in the city."
On Tuesday, two people were arrested after a ''despicable incident'' of violent disorder in Cardiff Bay as large numbers of people gathered on the hottest day of the year so far.
During the disturbance, which happened at around 10pm, bottles and other items were thrown at police leaving three officers with minor injuries.
Concerns have been raised that the recent gatherings could lead to a surge in Covid cases.
'Cardiff Bay' began trending on Twitter as videos and photos of the scenes were shared on Friday night.
On Wednesday night, the Welsh Government announced that pubs could reopen outdoor services from 26 April - subject to falling Covid rates.
It came as part of plans to move Wales fully into alert level three - meaning the coronavirus situation is still high risk.
According to Public Health Wales figures, there were 38 new cases of the virus reported in Cardiff on Friday - the highest anywhere in Wales.