A reported 10 percent stake in Deutsche Bank held by its biggest shareholder, Qatar's Al-Thani family, includes purchase options amounting to nearly 2 percent, a person familiar with the situation told Reuters on Monday.

The size of the stake was the basis for the nomination of lawyer Stefan Simon to the supervisory board of Germany's biggest lender last month.

That was made at the suggestion of Paramount Services Holdings and Supreme Universal Holdings, investment vehicles of Sheikh Hamad Bin Jassim Bin Jaber Al-Thani.

However, confusion surfaced over the weekend after a media report cited a court document as showing the Qataris held only 8 percent in the lender.

The person familiar with the situation told Reuters the Qataris held just over 8 percent in shares but also held nearly 2 percent in options, bringing their total stake to nearly 10 percent.

Deutsche Bank said the supervisory board nomination was based on the size of the stake reported.

"There is no reason to doubt it," the lender said, adding that it was the shareholder's decision in what form to hold the stake.

The Al-Thani family was not immediately reachable for comment. - Reuters