Porsche said in a statement that Qatar would buy 10 percent of the ordinary shares held by family investors in the company but did not reveal the financial terms of the deal.
The move is intended to facilitate a Volkswagen takeover of Porsche by 2011, the terms of which were agreed late Thursday. If the acquisition does not come to fruition, under the terms of the deal Qatar is entitled to resell its stake in Porsche back to the family dynasty that owns the legendary maker of the 911 sport car.
Qatar has also agreed to provide up to €265 million ($377 million) toward loans by a consortium of 16 banks. The Gulf state is to eventually become the third biggest shareholder in the new VW group, after the descendants of automobile magnate Ferdinand Porsche and the German state of Lower Saxony.
VW said earlier that Qatar's ultimate stake in the company would approach 20 percent and announced it would press ahead with a €4-billion capital increase next year in its bid to take full control of Porsche.
VW hopes to overtake Toyota as the world's biggest automaker by 2018. The two companies sealed a deal to tie up late Thursday, marking the end of an epic power struggle.
It was a clear victory for VW chairman Ferdinand Piech and the failure of Porsche's bid to take over their far larger rivals.