A Cumbrian abattoir was ordered to halt work after people living near the site complained of "horrendous smells".
The Environment Agency issued an enforcement notice to West Scottish Lamb Ltd on Carlisle's Brunthill Road on Monday.
The firm's operations resumed hours later after it took action to rectify emissions from the site's blood tank and piping.
An investigation into the cause of the problem is under way, he added.
Jon Mellor, Environment Agency regulatory officer, said: "Following a number of complaints from local residents and businesses we have taken swift action, and have issued the company with an enforcement notice.
"The company had to carry out the necessary repairs to resolve the situation and ensure that this does not happen again.
"We will continue to monitor the situation to see if any further action is required. Our investigation into the incident will continue."
Charles Kirkpatrick, a director at the firm, apologised to residents living nearby for the smells.
He said: "In the last two years we have spent a lot of money improving this problem and the last thing we would want to do is cause our neighbouring residents any inconvenience.
"It was an unfortunate incident yesterday and the engineers are here now sorting the tank.
"We are working as normal and the smell is no longer with us."