Bristol Zoo has said its staff are "very distressed" after a critically endangered Visayan warty pig and its piglet were killed by the newborn's father.

The animal conservation facility confirmed the deaths as it revealed there had been a couple of "very unfortunate and unforeseen" incidents there in the last three months.

The female pig called Manilla, who had arrived in July 2014, was joined by the male, Elvis, in September.

They got on well but she later showed some "subtle signs of behaviour changes", according to the zoo.

However, it said its vets did not think she was in the late stages of pregnancy.

Instead, they thought she was showing signs of a "false pregnancy" - and so the rare animals remained together.

However, she did give birth "very unfortunately and unexpectedly" at night and the male then attacked both piglet and mother, fatally injuring them.

Visayan warty pigs are endemic to two of the Visayan Islands in the central Philippines.

They are listed as critically endangered by the International Union for the Conservation of Nature, due to habitat loss, food shortages and hunting.

Meanwhile, a rare golden-headed lion tamarin monkey reportedly fell into a lake surrounding its zoo enclosure and then floated towards the otter enclosure where it was killed by otters three weeks ago.

And three lorikeet birds are thought to have managed to escape through a hole in their enclosure last week.

Two of the birds have apparently since been recovered but the zoo is still looking for the third.

In a statement, Bristol Zoo said: "We actively encourage natural animal behaviours and group dynamics. Our animals are also housed in natural enclosures, replicating environments they would be used to in the wild.

"As a result, on rare occasions, despite our best efforts, we are not able to prevent unfortunate and unforeseen situations from occurring.

"We are a conservation charity committed to ensuring the survival of endangered species in the wild as well as in human care. Such incidents are distressing for zoo staff, particularly for the keepers who care for the animals involved.

"The zoo is inspected regularly under the Zoo Licensing Act and adheres to the strict animal welfare and husbandry guidelines laid out by British Association of Zoos and Aquariums and Welfare Research Advisory Board."