Commodities trader Glencore , backed by partners Richardson International and Agrium Inc , has agreed to buy Canada's Viterra in a cash deal valuing the country's largest grain handler at C$6.1 billion (3.9 billion pounds)

Glencore said the deal offered C$16.25 per Viterra share and had been unanimously approved by Viterra's board. The price, broadly in line with market expectations after days of speculation, amounts to a 48 percent premium over Viterra's closing price on March 8, the day before it announced it had received expressions of interest.

Glencore, which is in the throes of a long-awaited $36 billion takeover of miner Xstrata , already markets and produces crops as well as metals, minerals and oil, but it has earmarked agricultural commodities as an area for growth.

The world's largest diversified commodities trader said it would pay for the deal using existing cash resources and credit facilities, but will also lighten the burden by selling the majority of Viterra's Canadian assets and some others to Agrium and Richardson for roughly C$2.6 billion in cash.

Agrium will acquire the majority of Viterra's retail agri-products busines, including its 34 percent stake in Canadian Fertilizer, for which it will pay C$1.8 billion. Richardson will acquire 23 percent of Viterra's grain handling assets as well as certain processing assets in North America for C$800 million.

The acquisition of Viterra reflects our strong belief in the importance and future potential of the Canadian and Australian grain markets, Chris Mahoney, Glencore's head of Agricultural Products said in a statement.

Viterra had said on Monday it was in exclusive talks with one prospective buyer, but did not identify a suitor.

Analysts have said a deal that splits Viterra three ways is unlikely to disrupt Glencore's blockbuster tie-up with Xstrata -- a prize it has been working towards for years -- and was instead a reflection of the trader's opportunistic approach to acquisitions. The Viterra deal comes as the Canadian Wheat Board's monopoly on Western Canadian wheat and barley is slated to end this year.

In Viterra, Glencore and partners will acquire the leading Canadian handler of spring wheat, canola, barley and oats.

Glencore describes itself as the one of the leading exporters of grain from Europe, the former Soviet Union and Australia. It commanded almost 9 percent of the global market for grains at the time of its listing last May.

(Reporting by Clara Ferreira-Marques; Editing by Chris Wickham)