China’s biggest hotpot chain Haidilao has offered to compensate more than 4,000 diners who visited one of its Shanghai branches, where two teens urinated into their hotpot broth.

A video of the boys peeing into their broth pot while dining in a private room was widely shared online last month. It is not clear who might have filmed the incident.

Police said the 17-year-olds, who were drunk at the time, were detained soon after the incident.

There is no suggestion anyone consumed the affected broth. Haidilao has apologised to customers, saying it has replaced all hotpot equipment and dining utensils, as well as disinfecting other crockery and utensils.

The incident happened late in February, though the company’s management only found out about it days later, after videos circulated on social media.

Haidilao said the staff on duty at the time had failed to stop the teens.

It took another week to find out which outlet it was, the company said, as it has dozens of outlets in the city.

Diners in Haidilao use their own personal hotpot equipment to cook their food, and broths are not re-used again for other customers. However, it is unclear in this case if the hotpot in question was thoroughly cleaned and disinfected before it was used by the next customer.

“We fully understand that the distress caused to our customers by this incident cannot be fully compensated for by any means, but we will do our utmost to take responsibility,” the company said in a statement.

Haidilao said customers who dined at the outlet between 24 February and 8 March will receive a full refund, followed by cash compensation that is 10 times the amount they were billed.

The company has expanded quickly since it opened its first restaurant in Jianyang in Sichuan province. It now operates more than 1,000 restaurants across the world.

Haidilao is known for its customer service and family-friendly atmosphere, where ladies can receive manicures and kids are treated to candy floss while waiting for a table.