SYDNEY, July 31 (Reuters) - EIG Partners is tapping international investors, especially Middle Eastern funds, to buy into one of its units that is part of a consortium taking over Australia's Origin Energy for $10.2 billion, according to two sources.

EIG, the U.S based investment firm, and its advisers have been holding negotiations for the past few months to bring on board equity partners to participate in the deal. The unit - MidOcean Energy - is a liquefied natural gas firm owned and managed by EIG.

EIG has joined a consortium led by Canada's Brookfield that has agreed a $10.21 billion takeover of Origin Energy which is Australia's second-largest power producer and energy retailer.

The sources, who have direct knowledge of the matter, could not be named discussing confidential information.

EIG, Origin Energy and Brookfield declined to comment.

If the deal goes ahead, MidOcean will take control of Origin's integrated gas business. It will also take on Origin's 27.5% stake in Australia Pacific LNG (APLNG) and has reached an agreement with ConocoPhillips to sell it a 2.49% stake in the project.

The talks with prospective investors have centered on Middle Eastern funds, which would be keen to buy into a major gas supplier which has long-dated, locked in contracts, one of the sources said.

The discussions are yet to be finalised and are similar in nature to EIG's Breakwater Energy, which bought in investors when it paid $4.8 billion for a 25% stake in Repsol's global upstream business. The transaction was completed in early March.

In that deal, Abu Dhabi's Multiply Group announced in July it had invested $100 million for a minority stake in Breakwater.

MidOcean in October paid $2.15 billion for Tokyo Gas’ interests in four Australian projects led by Gorgon LNG, Ichthys LNG, Pluto LNG and Queensland Curtis LNG. (Reporting by Scott Murdoch in Sydney; Editing by Sharon Singleton)