Negotiations with the Qatar Investment Authority (QIA), an investment fund, are focussing on the possible appropriation of non-listed voting shares or Porsche's potential VW options.
A deal could help Porsche clear some of its debt and strengthen its position in any future merger with the financially tight and much larger VW.
QIA and the Qatari government have not commented on the discussions.
Porsche amassed its debt when building up its current 51 per cent stake in the German VW.
It abandoned its attempt to take full control last month, after which the two firms said that they would discuss terms for a merger.
However, agreement between the Porsche and Piech families, who control both companies, stalled talks.
"If the talks are continuing, it is in a confidential manner," a VW spokesman said.
"For us, one thing is clear, any option that supports the goal of an integrated group with 10 brands, would be considered in a positive light."
If Qatar forges a deal with Porsche it would be the second major investment by a Gulf entity in the German auto sector.
Aabar Investments, a state investment fund in Abu Dhabi in the United Arab Emirates, bought a nine per cent stake in Daimler, the owner of Mercedes-Benz in March.
Porsche recently asked the German state-owned KfW bank for $2.43bn in credit, but has not received a reply.
During the past two years the firm made billions of dollars through dealings in VW shares, only to lose out heavily in speculative transactions which shouldered them with greater debt.