Fertilizer maker and input retailer Agrium has extended its offer to buy UAP while it waits for key green lights from U.S. and Canadian antitrust regulators.

The US$39-per-share offer for UAP’s publicly traded common shares — an offer that was set to expire at midnight, Jan. 8 — is now extended to midnight ET, Jan. 17.

Calgary-based Agrium said Wednesday that it’s extended its offer because “all of the conditions to completion of the offer have not yet been satisfied.”

Among those, it noted, are the waiting period under the U.S. Hart-Scott-Rodino Antitrust Improvements Act (also known as the HSR Act). That waiting period hasn’t yet expired or been terminated, Agrium said.

Agrium, which first announced its plans to buy Colorado-based ag input retail company UAP on Dec. 3, said Dec. 27 that it would refile its notification and report form under the HSR Act on Dec. 28.

At the time Agrium said the refiling would give it a “full 15-day period,” ending Jan. 14, to discuss and answer any questions coming from the U.S. Department of Justice or Federal Trade Commission.

Agrium also noted Wednesday that it hasn’t yet obtained the advance ruling certificate it needs under Canada’s Competition Act.

Agrium said in a release Wednesday that as of Jan. 8, about 44.42 million shares of UAP stock had been tendered into its offer and had not been withdrawn. That’s about 85 per cent of the company’s outstanding shares as of August 2007.

UAP shares (Nasdaq: UAPH) were trading at around $38.83 on Wednesday afternoon at 3 p.m. ET.

UAP runs about 370 distribution and storage facilities and three formulation plants, selling chemicals, fertilizer and seed to farmers, commercial growers and regional-level dealers across North America.

The company’s Canadian wing, based at Dorchester, Ont., includes warehouses in B.C., Quebec and Ontario and product lines of herbicides, fungicides, insecticides, nutrients, adjuvants, inoculants, growth regulators and other specialty products.

The deal would make UAP an Agrium subsidiary and would create the largest North American retailer of crop inputs and services, with broader geographic coverage as the two companies combine their “complementary footprints,” as they explained when the deal was announced last month.