LONDON-- Asia Resource Minerals PLC said Wednesday that the original separation deal from Bakrie Group is back on track after the major shareholder informed the mining company that it is now able to it is now able plug a funding gap.

Asia Resource Minerals, formally called Bumi PLC, said Indonesian conglomerate Bakrie Group had informed the U.K.-listed mining company it is able to raise the $228 million needed to complete the original separation deal by March 21. This marks a reversal from last week when Bakrie Group said it faced a $65 million shortfall and requested an amendment to the deal.

Asia Resource Minerals was formed in 2011, shortly after Bakrie folded its coal assets into an investment firm created by European financier Nathaniel Rothschild. The venture subsequently faced difficulties because of boardroom rifts over corporate governance, falling coal prices and an investigation into alleged financial irregularities at its Indonesian coal assets.

Bakrie Group decided to part ways with the London venture and proposed a separation deal in October 2012 that has since been revised many times before it was finally put to a shareholder vote.

Asia Resource Minerals said Wednesday it agreed to extend the closing deadline once again to March 21 from Wednesday, and it amended the deal so that Bakrie Group will now have to show proof by March 19 that it has put in escrow the entire $501 million needed to purchase Asia Mineral Resources' 29% stake in Indonesia's largest coal mining company, PT Bumi Resources TbK.

In December, Asia Resource Minerals shareholders backed a multistep deal in which Bakrie Group would sell its 24% stake in Asia Resource Minerals to two companies controlled by Asia Resource Minerals Chairman Samin Tan for $223 million. In a linked deal, Bakrie Group would then buy Asia Resource Mineral's 29% stake in PT Bumi Resources for $501 million.

Under the deal, Bakrie Group wasn't required to show any proof of funds until the day the deal closed, even though it would have to finance the $228 million to be paid in cash to Asia Resource Minerals after taking into account the $50 million already in escrow and the cash transferred from the Asia Resource Minerals stake sale to Mr. Tan.

Asia Resource Minerals now says Bakrie Group will have to put $451 million into the escrow account alongside the existing $50 million by March 19 for the deal to close.

The announcement "demonstrates ARMS PLC's board acting decisively and preventing minority shareholders suffering further losses of $65 million, " Mr. Rothschild said in a statement. "Assuming the separation transaction completes next month, we look forward to working with Samin Tan...to ensure that PT Berau fulfills its full potential." PT Berau Energy TBK is Indonesia's fifth largest coal producer and majority owned by Asia Mineral Resources.

The London-listed miner company said it won't extend the transaction deadline again and will terminate the separation deal if funding isn't received by the deadline. "In this context, the company is continuing to investigate alternative options to the separation transaction," it added.

Corrections & Amplifications Samin Tan is chairman of Asia Resource Minerals. An earlier version of this story incorrectly identified him as a former chairman.

Write to Alex MacDonald at alex.macdonald@wsj.com

Subscribe to WSJ: http://online.wsj.com?mod=djnwires