UPDATE 1-Luca Technologies withdraws IPO plans

* Cites adverse market conditions as reason for withdrawal

* Was planning to offer 8.5 mln shares at $11-$13/shr

April 23 (Reuters) - Clean energy company Luca Technologies has filed with U.S. regulators to withdraw its initial public offering, citing adverse market conditions.

"The current market, depressed natural gas prices and ongoing economic instability do not support an environment for us to complete an IPO," Chief Executive Bob Cavnar said in a statement.

The company was planning to offer 8.5 million shares in the IPO at an expected price range of $11 to $13 per share.

The Colorado-based company had filed with the U.S. Securities and Exchange Commission for an IPO of up to $125 million in June last year.

The company was expected to go public on March 30 but had been postponing it since then.

Luca uses its technology to stimulate micro-organisms residing in coal, oil, and organic-rich areas, accelerating the conversion of the fuels into methane, the principal component of natural gas.

Citigroup, Piper Jaffray and Raymond James were acting as the lead underwriters for the offering.

The company had applied to list its common stock on the Nasdaq under the symbol "LUCA."