The boss of Twycross Zoo says chimps were damaged by their appearance in TV adverts for tea.
Twycross Zoo has welcomed the birth of an endangered gorilla.
Endangered lemur twins have been moved to Twycross Zoo in an attempt to help the species breed.
A decision is expected over the next few days as to whether two former zookeepers should be charged with mistreating elephants at Twycross Zoo.
Three members of staff were dismissed and arrested in connection with mistreating the animals after the zoo reported its concerns to Leicestershire Police last year.
The elephants suffered no lasting ill effects.
– Crown Prosecution Service spokesman
"We've had evidence from Leicestershire Police about two of the people but a decision was taken some time ago against the third, determining no further action.
"A decision on whether to charge anyone in connection with the investigation would be taken in a matter of days."
Twycross Zoo's group of chimpanzees who made their way into an area of the zoo they should not have been in were offered ice cream and fizzy drinks as a bargaining tool.
Zookeepers at the Leicestershire zoo had to coax the animals out of the secure area this morning by offering them the sweet treats, which left them "a little excited."
The zoo was closed for less than two hours due to "safety procedures", but "no people or chimps were harmed during the incident".
Staff at Twycross Zoo have revealed how they tempted a group of straying chimpanzees back into their correct living areas:
Keepers encouraged the chimps back into their normal living areas with ice cream and fizzy drinks.
The zoo reopened at 11.30am today and all of the chimps are fine, if not a little excited about having ice cream for breakfast.
Twycross Zoo was closed to the public after "some chimpanzees" got into an area where they should not have been.
A spokeswoman for Leicestershire Police said: "A call came in at 9.35am from the zoo to let us know that some chimpanzees, that were in the process of being moved from one building to another.
"In the process of this they have perhaps gone into an area of that building that they shouldn't have been in.
"They don't appear to have actually physically escaped. As a precaution, we've been called by the zoo."
The spokeswoman said they stopped people going into the park for a "short time", and added that there was no danger to anyone in the park and no animals were on the loose.
Twycross Zoo has re-opened following an 'animal incident'. It has not be confirmed what animal was involved.
We can confirm there has been an incident involving one of our animals. Twycross Zoo's team are working to... http://t.co/CYPFwjQZXS
A spokesperson for Twycross Zoo say they are dealing with an 'animal incident' on site and the zoo is currently closed to the public:
– Twycross Zoo
We're currently resolving an animal incident on site and the zoo will be closed to the public until further notice.
– Twycross Zoo
We can confirm there has been an incident involving one of our animals. Twycross Zoo's team are working to resolve the situation as quickly as possible, whilst ensuring the safety of the public and staff. The zoo is closed at present however we anticipate the zoo will reopen today and we will update you at 12 noon.
Thousands of people have flocked to Twycross Zoo for a family fun day in honour of its 50th anniversary.
The Summer Sundown Party, which is being held today and tomorrow, features live music, local traders in a vintage craft market and a 1960s themed school sports day.