The Ohio zoo at the centre of an animal rights storm has closed its Twitter and Facebook accounts after trolls targeted it over the death of the gorilla Harambe. Cincinnati Zoo was heavily criticised after it shot and killed the gorilla after he was pictured grabbing and dragging a three-year-old boy who had got into his enclosure in May.

As part of the social media furore, more than half a million people signed a petition calling for "justice for Harambe".

The globally-renowned British primatologist, Jane Goodall, contacted the zoo to say it looked like the animal was not trying to attack the boy, but protect him.

Social media users have also been sending jokes and other comments spurring the zoo management to claim it had been relentlessly harassed over the death of the 440-pound (200kg) silverback.

Zoo director Zane Maynard told Associated Press: "We are not amused by the memes, petitions and signs about Harambe. Our zoo family is still healing.

"We are honouring Harambe be redoubling our conservation efforts and encouraging others to join us," he said. On Tuesday 23 August, the zoo's account on the micro-blogging site had been deleted. Its Facebook account had also ceased.

The accident happened on 28 May, when the boy fell into the moat at the Gorilla World enclosure and was dragged around by Harambe. He suffered concussion and a few scrapes but was largely unharmed. The zoo reopened the exhibit after building a higher barrier.

There was also an online petition criticising the boy's mother, Michelle Gregg, who defended herself by saying on twitter: "As a society we are quick to judge how a parent could take their eyes off of their child. If anyone knows me, I keep a tight watch on my kids.

"Accidents happen but I am thankful that the right people were in the right place... What started off as a wonderful day turned into a scary one."

Silberback gorilla Harambe
The killing of silverback gorilla Harambe has been defended by the director of Cincinnati Zoo Reuters/Cincinnati Zoo