Sibanye, Northam among bidders for Anglo's Union mine-sources

* Anglo aiming to sell for $200-300 mln-source

* Northam helped by experience in platinum mining

* Weak platinum prices could curb bids

By Silvia Antonioli and Anjuli Davies

LONDON, Dec 3 (Reuters) - South African precious metals mining firms Sibanye Gold and Northam Platinum (Other OTC: NMPNF - news) are among a shortlist of about 10 companies interested in Anglo American Platinum's Union mine in South Africa, mining industry sources said this week.

Anglo American Platinum (Amplats), a unit of global miner Anglo American (LSE: AAL.L - news) , kicked off the sale process for the Union mine and concentrator in October as part of its attempt to shift away from old, deep, labour-intensive mines to newer, more mechanised mines such as open pit Mogalakewna.

A first round of bids is expected early next year, one of the sources said.

The Union mine, one of Amplats' worst-performing, had an operating margin of 1.4 percent in 2013 compared with a 36 percent margin for Mogalakwena.

A second source said Amplats would be looking to sell the mine for around $200-$300 million but that the current weakness in the platinum price may curb bids.

"It's not exactly a seller's market at the moment," he said.

Platinum fell to a five year low last month and is hovering around $1,220 an ounce, well below its 2008 peak of nearly $2,300.

Another source said he thought Johannesburg-listed Northam, a mid-tier producer, had more chances of success than the other bidders given its experience.

"Northam would be the ideal candidate, they already operate in platinum nearby and they do know how to mine that ore body," he said.

Northam said in August that it was looking to snap up platinum assets in a shake-up of the country's platinum sector.

Gold producer Sibanye, a spin-off from bullion miner Gold Fields that specialises in operating deep underground mines, also said earlier this year it planned to make an acquisition in platinum.

A spokesman for Anglo American declined to comment. Sibanye and Northam were not immediately available to comment.

(Editing by Michael Urquhart)