Steel giant ArcelorMittal and US company Peabody Energy sweetened their offer for Australian coal miner Macarthur Coal, the firms said on Thursday. ArcelorMittal and Peabody said they would include a dividend payment of up to Aus$0.16 to Macarthur shareholders in their $15.50 dollars (11.74 euros, $16.67) per share offered in the first proposal. In the first offer, announced on Monday, Macarthur\'s 2011 dividend was to be taken out, valuing the company at $Aus4.7 billion or 3.5 billion euros, depending on the exact dividend payout at the end of the year. ArcelorMittal and Peabody also announced that Macarthur had accepted a due diligence request, that can begin next Monday. In due diligence, the two companies have access to Macarthur\'s financial books and can visit Macarthur mining sites, and is an important step towards finalising a takeover agreement.