* Takeover bid at A$15.50/shr, 40 pct premium to Monday's close
* Peabody attempt comes a year after it dropped A$16/shr bid
* Bid also follows new Australian carbon tax on miners, others
* Macarthur advises shareholders take no action
* Macarthur to talk to Peabody, ArcelorMittal on terms (Adds detail, analyst quote, arcelor statement)
By Narayanan Somasundaram
SYDNEY, July 11 (Reuters) - Peabody Energy has teamed up with ArcelorMittal to offer $5 billion for Australia's Macarthur Coal , the world's biggest producer of pulverised coal, as demand for steel-making raw materials intensifies.
The cash offer of A$15.50 a share represents a 40-percent premium to Monday's close and comes just a day after Australia unveiled a plan to tax carbon emissions from the nation's worst polluters, or about 500 companies, including coal miners.
It also comes amid a flurry of activity in takeovers involving Asia-Pacific companies, with at least four multi-billion-dollar deals announced on Monday alone, and marks further consolidation within the coal sector.
Macarthur, named after U.S. General Douglas MacArthur, made no recommendation on the proposal and said it would seek talks with Peabody and Arcelor on price and terms. The position of China's Citic, a key shareholder, was not immediately clear.
Macarthur was the subject of a three-way bidding war in 2010 when it agreed to enter talks with Peabody, the highest bidder with an A$16 offer. However, talks collapsed after Peabody cut its offer when the centre-left Labor government slapped coal and iron ore miners with a mining tax.
Analysts said there important differences this time round.
"Now they have Arcelor, which is actually a shareholder and they've locked away some pre-bid acceptances for the first time. That's got to give them more comfort," said CLSA Asia Pacific Markets mining analyst Hayden Bairstow in Sydney.
Peabody, already one of Australia's larger coal miners, is pursuing an aggressive growth strategy outside the United States and has committed to doubling its Australian presence.
ArcelorMittal, the world's largest steel company, meanwhile, is boosting its iron ore and metallurgical coal asset portfolio in an effort to ease the pain of rising fixed and raw material costs that have hit the entire steel sector.
"It is clear in (Arcelor's) strategy that they have to backward integrate, and that means getting more involved in metallurgical coal and iron ore mining," said analyst Scott Finlay at Daiwa Capital Markets in London.
"Macarthur is the world's biggest low volatile PCI producer, it has large resources in Queensland -- nice, simple open-pit operations - and low costs. It makes strategic sense to increase the stake."
PCI coal, which is crushed into a fine powder and injected into blast furnaces, is used as a replacement for coke in the production of pig iron.
ArcelorMittal and Peabody said they would make their takeover proposal through a bid company, with ownership split 40 percent and 60 percent, respectively.
ArcelorMittal is the second-largest shareholder in Macarthur with a 16.2- percent stake, according to its website.
But the support of China's Citic, the largest owner with 24 percent, will be critical, as the proposal is conditional on winning acceptances for more than 50 percent of the company.
Citic Resources Australia, a unit of Citic, plans to study the proposal and has not yet taken a decision, its managing director told Reuters. .
The timing of the offer caught some investors by surprise. The deal was unveiled just a day after the Australian government's new carbon levy, and as the company recovers from recent flooding of its mines.
Analysts, though, said the tax has long been expected in the market and was unlikely to weigh on the deal at current lofty coal prices -- unless the government begins to raise the levy.
"This deal looks opportunistic," said Tim Schroeders, a portfolio manager at Pengana Global Resources Fund. "The carbon tax was just announced yesterday and with Peabody's involvement again, investors will be cynical. They cut their offer right after another big tax last year," Schroeders said. He declined to say if he owned Macarthur shares.
Despite environmental concerns, the global market for coal is healthy, with prices for the pulverised coal mined by Macarthur trading at a narrowing discount to hard coking coal. Spot prices for coking coal and PCI, pulverised coal injection-type coal, have softened in recent weeks on the back of slower Asian demand, but this is expected to be a short-term blip.
In fact, the deal is a substantial bet on strong and steady demand in Asia, from China and India but also other countries where steel growth is forecast to be strong. Any big downturn would be bad news, as production would then get sold for power generation, at less than half the coking price.
It was unclear on Monday whether other suitors could step in to once again scupper Peabody's efforts. Australian miner New Hope said a year ago, after the takeover battle, that it was still interested in Macarthur.
Companies globally are searching for opportunities to put hefty cash piles to work and a slew of further deals were announced on Monday. Among the larger offers, Nestle , the world's largest food company, offered to buy 60 percent of Chinese candy maker Hsu Fu Chi International for about $1.7 billion and a group owned by Hong Kong's Li Ka-shing made a proposal for Northumbrian Water valuing it at 2.4 billion pounds ($3.9 billion).
Macarthur shares, which closed at A$11.8 on Monday, peaked above A$21 in 2008.
The deal values Macarthur's 1.64 billion tonnes in reserves at nearly A$3 per tonne. Rio Tinto's purchase of Riversdale earlier this year valued its coking coal-dominated reserves at A$0.49/tonne while Macarthur paid A$1.68/tonne when it bought some coal mining assets a year ago, according to a report from Morgan Stanley.
Macarthur is being advised by JPMorgan, ArcelorMittal is being advised by RBC Capital Markets and Peabody has engaged UBS and Bank of America Merrill Lynch. ($1 = 0.930 Australian Dollars) (Additional reporting by James Regan in SYDNEY, Denny Thomas and Alison Lui in HONG KONG, Clara Ferreira-Marques and Jackie Cowhig in LONDON; Editing by Balazs Koranyi, Lincoln Feast and Sitaraman Shankar)