A rhino has been shot dead by poachers who broke into a zoo and sliced its horn off with a chainsaw.

Four-year-old Vince was found dead by one of his keepers at Thoiry zoo, near Paris, on Tuesday morning.

One or more attackers are believed to have broken into the zoo in the night.

The rhino was shot three times in the head, French investigators said.

Staff at the zoo are said to be "extremely shocked" and an investigation into the killing is under way.

Vince's second horn was partially cut, which the zoo said suggested either his attackers were disturbed or their chainsaw stopped working.

"This odious act was perpetrated despite the presence of five members of the zoological staff living on the spot and surveillance cameras," the zoo wrote on its Facebook page.

"The other two white rhinoceros living in Thoiry, Gracie aged 37 and Bruno aged five years, escaped the massacre and are safe."

It is believed to be the first attack off its kind at a zoo in Europe, the post added.

Vince was born in late 2012 at Burger Zoo in The Netherlands and had been at Thoiry, situated 30 miles west of Paris, since March 2015.

France's environment minister Segolene Royal said: "The killing of a rhinoceros at Thoiry is criminal.

"It is time countries outlaw the trade in ivory and horn as I have done in France."

Ivory horns can be sold on the black market for tens of thousands of pounds.

Southern African countries are battling increased poaching levels as organised gangs from mainly Asian countries try to meet the growing demand from countries such as Vietnam and China.