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Macquarie leading bidder for Bayer's chemical park operator - sources

* Bayer selling 60 pct stake, Lanxess to stay invested

* Deal to value Currenta at more than 2 billion euros -sources

* Deal expected in a few weeks time -sources (Adds details, background)

By Arno Schuetze and Ludwig Burger

FRANKFURT, March 1 (Reuters) - Macquarie has emerged as the leading bidder for Bayer's 60 percent stake in chemical park operator Currenta, which the German drugmaker has put on the block to reduce its debt pile, people close to the matter said.

Talks between Bayer and the Australian bank's Macquarie Infrastructure and Real Assets (MIRA) arm will likely continue for a few more weeks and the deal could still fall apart given the complexity of the negotiations, they added.

If no deal emerges, Bayer may fall back on runner-ups DWS and KKR, the sources said, adding that it was unclear whether the Ontario Municipal Employees Retirement System, which also made a final bid in January, was still interested.

Bayer, Macquarie, KKR and DWS declined to comment, while Omers had no immediate comment.

Currenta is expected to be valued at well above 2 billion euros ($2.3 billion), including debt, the sources said.

Bayer initially planned to sell the Currenta stake - a legacy asset with little benefit for its core drugs and agriculture businesses - to its former industrial chemicals subsidiary Covestro, but could not reach an agreement on valuation.

Covestro and Lanxess, both former Bayer businesses, are Currenta's main customers.

Lanxess, a maker of additives, drug ingredients and leather-tanning chemicals, holds the remaining 40 percent in Currenta. It has a right of first refusal for the remaining shares but has said it would keep its current holding unchanged.

Bayer has launched a slew of asset sales to reduce debt after the $63 billion takeover of U.S. seed maker Monsanto.

Currenta runs the infrastructure at western German chemical complexes in Leverkusen, Dormagen and Krefeld-Uerdingen, which were once dominated by Bayer.

Talks with Macquarie are focusing on a slew of topics such as the exact size of the asset, the status of the property and future dividend policy, the people said.

It is competing with larger pharma rivals as it bids for the rights to promising new treatments from biotech firms to try to strengthen its drugs development pipeline.

Currenta serves more than 70 customers with 3,200 staff, providing electricity, steam and natural gas as well as services such as transportation, maintenance and waste management. ($1 = 0.8790 euros) (Editing by Thomas Seythal; Editing by Elaine Hardcastle)