The discount voucher website Wowcher has apologised after appearing to make reference to a crocodile attack on a toddler at a zoo in an email promoting its offers.

A spokesperson for Wowcher said it was urgently reviewing its marketing content after the subject line of an email on Saturday urged customers to “Snap up these deals quicker than a croc can catch a kid!”

A three-year-old was taken to Addenbrooke’s hospital in Cambridge, after an incident at Old Hurst zoo in Huntingdonshire on Thursday lunchtime during which the boy ended up in an enclosure with Nile and saltwater crocodiles.

The toddler was taken to hospital with serious injuries. He is in a critical but stable condition. A 30-year-old man from Norfolk has been bailed while further inquiries take place.

Wowcher said it was “extremely sorry” for the “unacceptable” wording.

In a statement a spokesperson said: “It should never have been written, it was never approved for use. The responsibility sits with us and we are urgently reviewing how our processes failed.

“We recognise the hurt and distress it has caused, particularly for the young child’s family at this unimaginably difficult time.”

They added: “We are reviewing all scheduled marketing content while we urgently strengthen our creative, approval and signoff safeguards.

“There is no excuse for this. We apologise unreservedly and will take the necessary steps to make sure this does not happen again.”

The Times reported on Sunday that detectives were scrutinising CCTV from the zoo to establish whether they would take further action.

The man arrested on suspicion of attempted murder has been released as detectives believe he is not fit to be interviewed, police said on Friday.

He was not known to the alleged victim. He has been bailed until 18 September.