Not many small exploration companies would knock back a...

Not many small exploration companies would knock back a multi-million-dollar financing offer by BHP Billiton (BHP) , the world's biggest mining company, but Nick Mather of Ecuador-focused SolGold Plc said he has better offers.

Interest in Solgold's Cascabel copper and gold project has already led to a $33 million deal with investment bank Maxit and Australian gold miner Newcrest (NCM).

"BHP certainly wants the asset," SolGold Managing Director Nick Mather told Reuters on Tuesday. "But it's not what we are looking for."

BHP on Saturday offered $30 million, or 22 cents per share, for a 10 percent stake in SolGold, which SolGold rejected.

The offer included an additional $275 million proposal, linked with acquiring a much larger stake in the unit managing the Cascabel project, Exploraciones Novomining (ENSA).

"The deal BHP was offering was very inadequate because we would lose 70 percent of the upside," Mather said.

SolGold holds 85 percent of ENSA, and 11 percent of Cornerstone Capital Resources , which owns the remaining 15 percent of ENSA.

Based on early exploration work, Mather believes SolGold may have made a major new high-grade copper and gold find to rival some of the largest existing mines, such as Grasberg in Indonesia, controlled by Freeport McMoran Inc , and Oyu Tolgoi in Mongolia, controlled by Rio Tinto (RIO) .

BHP's attempt to take control of SolGold comes just ahead of a Oct. 13 shareholders' vote on whether to approve the Newcrest and Maxit offers.

"Barring the arrival of superior offer, we will be approving the Newcrest and Maxit transactions," Mather said. "Newcrest and Maxit understand what we want."

Major mining companies are spending big to find more copper. Copper is the most sought-after industrial metal, as existing mines age and new ones are found in increasingly difficult locations.

Rio Tinto in the past year has undertaken a $5.3 billion expansion of the Oyu Tolgoi copper mine. Anglo American has designated copper as only one of three commodities where it sees a future for the company.

SolGold marked BHP's first attempt to boost its copper assets via an acquisition since Managing Director Andrew Mackenzie unveiled a corporate shift in growth strategy this year away from iron ore mining, with a focus on copper and oil.