According to the industry regulator, Mr Cameron was responsible for the firm making inaccurate announcements regarding payments to Chalva Tchigirinski, one its largest shareholders.
While under the tenure of the former-CEO, Sibir provided incorrect figures for payments made to the latter in December 2008 and February 2009.
By stating that the firm had paid $115.4 million rather than the actual figure, which in both instances was over $300 million, the markets were misled as to the value of Sibirâs assets and its exposure to risk, the FSA explained.
Margaret Cole, director of enforcement and financial crime at the FSA, said: "As the most senior executive director at Sibir, Cameron should have known these announcements were misleading and the serious impact they were likely to have on the market.
âOur fine reflects the gravity of his irresponsible actions and shows that we are serious about taking action against directors of publicly traded companies who commit market abuse. It is not acceptable for directors to take action which is in the interests of some shareholders while keeping others in the dark."
Mr Cameron was suspended from his post by Sibir in February 2009 before being let go two months later.
The FSA did not impose any financial penalty on Sibir.
By Jim Ottewill