08/05/2012 12:03 BST

Connyland Dolphins: Zoo Manager Blames 'Planned Strike', Animal Activist Conspiracy For Dolphins' Death

The owner and general manager of Connyland zoo has denied that two dolphins died from ingesting a heroin replacement drug, instead blaming a "planned strike" against the zoo by animal activists.

In an email to the Huffington Post UK, Roberto Gasser denies that the death of the Swiss zoo's two dolphins had anything to do with a party near the site days before.

"They [the dolphins] died two weeks after the party," Gasser wrote, "so the party had nothing to do with it at all.

"This is an untrue story let out by animal activists which might be the cause of the death of our animals."

According to a toxicology report on the dolphins, buprenorphin, a heroin substitute drug, was present in the animals at the time of their death, but Gasser denies this has anything to do with the party.

MORE: 'Connyland Dolphins Died After 'Heroin' Overdose During Techno Rave'

Gasser said that the reports linking the deaths to the party are "in parts very untrue". He blamed the Wal- und Delfinschutz-Forum (WDSF, which translates to the Whale and Dolphin Protection Forum) for the false reports.

He states that the has zoo rented its sound-proofed chateau for discos every weekend for the past decade, without any harm done to any animals.

"Even though some animal activists did state that it would harm animals... out state vetinarian and all kinds of media were in our dolphinarium during the night we hosted the disco party. Nothing was heard or disturbed the animals."

It is still unclear how the dolphins came to ingest the buprenorphin found in the post-mortem toxicology report but Gasser claims that as the dolphins are only ever given medication with their food, it must have been given to the dolphins that way.

He claims that signs of forced entry at the food preparation show that the dolphins' deaths were an "attack" and "a planned strike against us."

Gasser closed by insisting that the zoo has worked with dolphins for over 35 years, "and our animals always come first."