Abel said that as the contents of the letter had not been made public, there was no proof that it was motivated by environmental motives.
In reality, he said, New Zealand's major environmental organisations -such as Forest and Bird- actively endorsed the use of 1080.
He said he had been impressed with the Police's "dispassionate" and "appropriate" response to the threat.
"When they were asked directly about that term "eco-terrorism", they said well, we wouldn't call it that. It's blackmail."
Terrorism, regardless of the motive, was unacceptable, Abel said, and the threat of poisoning infant formula a "terrible thing".
"In a way Key diminishes the seriousness of it by using it as political opportunity to attack a section of society with who he is in disagreement."
Abel said Key had an "appalling record on the environment" and the environmental movement was "frankly a thorn in his side because we don't sit back while he risks everything we hold dear in this country".
In a post to his personal Facebook page on Tuesday, following Key's statement, Abel gave ten reasons why Key was "New Zealand's number one eco-terrorist" - which he told Element could refer to both people associated with the environmental movement and those harming the environment.
Abel said he was motivated to write the post after he watched Tuesday's press conference and felt that Key's statement was just "dodgy politics".
The post said:
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