“There has been no evidence that I used chemical weapons against my own people,” CBS reported Assad said in an interview conducted in Damascus.
“There has been no evidence that I used chemical weapons against my own people,”
The speaker’s use of “has been” is not the same as “there is none”. This indicates he knows there is evidence, just that it has not surfaced.
Assad’s use of “evidence” is known as attacking the procedure. He does not deny that chemical weapons have been used, he simply asserts the evidence is not available. This is not a declaration that he didn’t do it- it’s a statement that you can’t prove it.
The speaker states “I used…”. This may be true. However, it may have been his military, acting on his orders that did use the chemical weapons. People tell lies as close to the truth as possible in order to be more convincing and to make their job easier.
Assad states “… my own people.”. He may not consider the rebels as his people, again letting himself off the hook psychologically.
I would expect an honest denial to be along the lines of “I didn’t order, nor did my military deploy chemical weapons against any rebels or civilians. There is no proof and there never will be because it didn’t happen.”
As a disclaimer, this is just a small sample of Assad’s statement (not released in full yet) and he is not a native English speaker which must be taken into consideration. That being said, analyzing only the information that we have, I would choose not to believe Assad’s statement.