Hamerton Zoo, where a keeper was killed after a tiger entered the enclosure she was in, had been told by inspectors to improve its emergency communications systems, it is reported.
Rosa King, 34, died in a "freak accident" at the Hamerton Zoo Park in Huntingdon, Cambridgeshire, on Monday.
The long-serving zookeeper was described as "inspirational" and enjoyed working with her "beloved cats", friends said, while her mother said she "wouldn't have done anything else" as a career.
The Telegraph said the zoo had been criticised following an inspection in 2013 - which ordered the owners to "review and replace ageing safety barriers where the structural integrity of the barrier is compromised".
The report, quoted in the paper, added: "Inspectors consider that reliance on mobiles to communicate in an emergency is not sufficient and the system needs to be upgraded to ensure that all relevant staff can be contacted simultaneously."
Owners were also tasked with tailoring escape procedures to the various risks posed by animals at the zoo.
The zoo is said not to have responded to the paper's requests for comment.
Distressed staff are said to have thrown meat into the enclosure in a desperate attempt to help Ms King during the incident on the morning of Bank Holiday Monday.
Ms King's mother Andrea told the Press Association her daughter had worked at the zoo for around 14 years, adding: "She wouldn't have done anything else, it's what she has always done, it's what she has always loved."
Ms King's mother asked for the family's privacy to be respected.
Cambridgeshire Police said the tiger had not been killed and was unharmed.
The gates to the attraction, which is in a rural lane surrounded by open fields, were locked on Tuesday morning as an investigation continued.
The zoo, which saw visitors evacuated when the incident occurred, said what happened appeared to have been a "freak accident".
It said: "At no point during the incident did any animals escape their enclosures and at no point was public safety affected in any way.
"All our thoughts and sympathies are with our colleagues, friends and families at this dreadful time."
One witness, Pete Davis, told BBC Radio 5 live: "You could obviously see the keepers were all distressed and, you know, not really knowing what to do, heads in their hands.
"A couple of them were throwing meat over the enclosure to try and entice the tiger away."
Some of those who knew the killed keeper have paid tribute to a woman they described as a "central point" of the zoo.
Garry Chisholm, 59, a wildlife photographer in his spare time who knew Ms King through visiting the attraction, said the place revolved around her.
Mr Chisholm, from Irchester, Northamptonshire, said on Monday: "Rosa wasn't just a keeper at Hamerton Zoo - she was Hamerton Zoo.
"She was the absolute central point of it, the focal point of it. She was the shining light of it.
"It revolved around her."
He added: "Her passion for the animals in her care was exceptional, though her favourites were undoubtedly the cheetahs which she would refer to as her pride and joy.
"The only consolation I can take from today's tragic events is that Rosa is now reunited with her beloved Ares the cheetah, and Blizzard and Ladybelle, her beloved tigers."
Philip Caso, a 20-year-old zoology student from Peterborough, got to know Ms King through doing work experience at the zoo each summer and commended her conservation efforts.
In a tribute on Facebook he wrote: "I'm literally devastated to hear that one of the most inspirational women I knew died at Hamerton Zoo.
"Rosa loved and respected those animals to the point where each and every one was like a child to her. Her passion for her job has really inspired me and I was just glad I got the chance to know her. Thinking of all the other keepers."
Photographer Hollie Gordon, who said she became friends with Ms King through visits to the zoo, said: "Her passion for the animals, the zoo and conservation really shone through. She loved them all!"
The 24-year-old, from Blackpool, added: "I am in shock by what has happened. Terribly upset and can't quite believe I won't see her again with a big smile on her face and working with her beloved cats."
The case has been referred to Cambridgeshire Coroner's Office where a spokesman said an inquest would be opened next week.