Australia's Macarthur Coal postponed a shareholder vote on whether to take over a smaller rival, leaving the door open for major coal producers to bid for Macarthur, the world's top producer of a cleaner coal sought after by steelmakers.

Macarthur earlier on Friday rejected a $3.5 billion bid from local rival New Hope Corp , and recommended shareholders approve a plan to take over Gloucester Coal in a deal that would see commodity trader Noble Group take an around 25 percent stake in Macarthur.

Brisbane-based Macarthur Coal, led by CEO Nicole Hollows, has prompted frenzied bidding as coal majors eye its specialist pulverized or PCI coal, a cleaner input for steelmakers' blast furnaces.

The frantic maneuvering around the world's biggest exporter of PCI coal follows a flurry of deals in Australia, where the number of big independent coal producers is dwindling as bigger players make acquisitions to meet booming Asian demand that has driven up coal prices.

New Hope offered 2.7 of its shares for every Macarthur share -- valuing its target at A$14.58, a 4.1 percent premium to an earlier A$14 a share offer for Macarthur from St.Louis-based Peabody Energy , the world's largest private-sector coal producer. Macarthur rejected that bid earlier this week.

Macarthur said the New Hope offer was inadequate.

Macarthur later said it put back Monday's vote on the Gloucester deal to April 19, noting London-listed Xstrata Ltd , the world's biggest exporter of coal for power plants, had approached one of its major shareholders.

Other shareholders wanted a delay so they could digest all the information the company had recently disclosed, it added.

I'm not surprised that Xstrata entered the arena, said Andrew Pedler, mining analyst at Wilson HTM. It's always grown by acquisition, but usually does cash offers, he said, adding he didn't expect new bidders to jump into the fray.

There's enough with three contenders.

Xstrata declined to comment.

SHARES JUMP

The bidding war for Macarthur sent its shares up nearly 12 percent on Friday in heavy trading that was nearly eight times the daily average. The stock hit A$16.03, its best since August 2008, in a largely flat broader index <.AXJO>.

New Hope shares slipped 0.2 percent to A$5.30.

Macarthur is developing a coal mine at West Rolleston, in central Queensland, which is just 25 km away from a mine being developed by Xstrata. Macarthur also recently appointed a new finance chief, Ian Fuller, who was previously at Xstrata Coal.

Both Peabody and New Hope made their approaches conditional on Macarthur not going ahead with the Gloucester/Noble deal.

Noble was not immediately available to comment.

I think the Gloucester deal is attractive, but New Hope should be carefully considered as it's a scrip offer, noted Pedlar. With cash offers, investors have no further part in the upside of the company.

Macarthur's top three shareholders -- China's CITIC Resources Holdings <1205.HK> and steel giants ArcelorMittal and POSCO <005490.KS> -- own a combined 47.3 percent stake in Macarthur - and are key to what happens next.

Steelmills would prefer Macarthur to not be swallowed by a major coal producer, said an analyst, who declined to be named as he does not cover ArcelorMittal or POSCO.

But if they decide to get into bed with one, they'd make sure it doesn't have a big presence in coking coal.

Macquarie and Morgan Stanley have said in research notes this week that a buyer may need to offer closer to A$16 a share to win Macarthur minority shareholders' support.

Macarthur produced 4.6 million tons of coal last year.

(Additional reporting by Koh Gui Qing and Narayanan Somasundaram, Editing by Ian Geoghegan)

($1=1.077 Australian Dollar)