The BC Liberals started working on a harmonized sales tax just three days after winning last May's election, federal Access to Information documents show.

The documents obtained by The Canadian Press show bureaucrats from the B.C. Finance Ministry contacted federal Department of Finance tax officials on May 15 with an information request regarding the HST.

B.C. Finance Minister Colin Hansen has said the Liberals didn't consider the HST until after the May 12 vote, but the documents show for the first time just how quickly the idea to implement the tax came up.

The province publicly announced last July it had reached an HST deal with Ottawa.

Most of the more than 800 pages of HST documents released under the federal Access to Information request were left blank.

The reasons were cited as rules that allow governments to withhold information obtained in confidence and refusal to disclose federal-provincial consultations and deliberations.