* September deadline for $1 bln Almatis restructuring

* Distressed debt investor Oaktree backs owner ahead of deal

* Twin-track strategy means sale still possible

(Adds response from company, adds detail to payment request)

By Tom Freke

LONDON, July 10 (Reuters) - Lenders to German alumina company Almatis [ALMTI.UL] have until September to agree a restructuring of its debt pile or a sale of the company, sources close to the situation said on Friday.

Almatis needs to make payments by the end of September to former owner Alcoa (AA.N: Quote, Profile, Research) to pre-fund this year's commitment to its feedstock supply contract, two of the sources said.

"They are looking to fix their balance sheet before the payment is made, so that's the reason for the urgency," one of the sources added.

A spokesman for Almatis denied the company needed to make the payment before the feedstock was delivered.