MELBOURNE (Reuters) - Anglo American on Wednesday rejected BHP Group's last-ditch request for more time to discuss a $49 billion takeover offer, dismissing it as highly complex and likely ending a five-week pursuit by the bigger rival.

Anglo had granted BHP a one week extension until 1600 GMT on Wednesday to its original May 22 deadline to submit a binding offer, after rejecting a third takeover proposal that it dismissed as difficult to execute.

BHP still has until then to make a firm offer or walk away.

BHP's shares closed flat on Wednesday at A$45.08. Anglo's were down 0.7% at 25.39 pounds by 0915 GMT.

London-listed Anglo agreed to hold talks with BHP to try to iron out concerns over the structure of the proposed deal, namely its condition that Anglo unbundle its South African platinum and iron ore units before the takeover.

In an earlier statement, BHP said it needed more time to engage with Anglo, while outlining commitments to minimize regulatory risk in South Africa.

Those commitments included job security for employees in South Africa. BHP also said it would shoulder the costs of increased South African employee ownership that is expected to be required in any demerger.

"Throughout the engagements with BHP, BHP continues to restate its belief that the risks of its complex structure are not material, yet has repeatedly and consistently stated both publicly and during the engagements that it is unwilling to amend its proposed structure to assume these risks," Anglo said in its statement.