The New York Mercantile Exchange (search) is considering buying its Internet-based rival, the IntercontinentalExchange (search), for up to $350 million in a deal that would consolidate two major players in the energy futures trading market, a source with knowledge of the situation said.

An offer stating how much NYMEX would be willing to spend to form an alliance with Atlanta-based ICE was extended within the last several weeks, the source said Wednesday on condition of anonymity.

ICE has not yet responded to the offer, which is preliminary and meant as a starting point of discussions, the source said. ICE spokeswoman Kelly Loeffler did not return several phone calls seeking comment. NYMEX officials declined to comment.

The offer was first reported Wednesday by The Financial Times.

The New York Mercantile Exchange is the world's largest commodity futures (search)exchange, trading energy and precious metals.

IntercontinentalExchange is an over-the-counter, Internet-based energy and metals exchange. Its subsidiary, the London-based International Petroleum Exchange (search), is Europe's leading energy futures and options exchange.

The exchanges have benefited in recent months from surging oil prices.