Sorry to post to you twice back-to-back, but I found this and thought you might be interested:
http://209.157.64.200/focus/f-news/994966/posts
The further discussion states that the Polish government accepted that these missiles were pre-1990. Who knows whether that was true.
Its also possible that much equipment was supplied via third parties, cut-outs, and "illegally" from third-country stocks. The US did in fact supply Iran with missiles and spare parts in the 1980's that way. It kept the Iranian airforce viable.
It is very difficult to prove that a government is doing this sort of thing deliberately.