Iran: Mossad's involvement in blast a myth

They say so themselves:

Iran's Parliament Speaker Ali Larijani addressed reports claiming that the Mossad was behind the blast at a military base near Tehran and said that they were "myths."

On the other hand:

Iranian armed forces chief of staff Hassan Firouzabadi also denied that Israel was behind the blast. Speaking to ISNA he said that the blast occurred during research on weapons that could strike Israel.

There must be a lesson somewhere in that statement...