LONDON, April 20 (Reuters) - Petra Diamonds (PDL.L) is working to reduce any market impact if major shareholder Saad Investments Company Ltd were to sell its stake, by lining up potential buyers, its chief executive said on Tuesday 20 April.

Liquidators were appointed last year for Saad Investments, a unit of Saudi investment firm Saad Group [SAAD.UL]. Saad has a 17 percent stake in Petra. "One concern is the Saad holding," Johan Dippenaar told a diamond conference in London.

"They are in administration, and together with our brokers we are working very hard to make sure that if that block comes to the market, it comes in an orderly fashion.

"As we stand now, they have no intention to sell it, and we have a number of people lining up to take that block should it come to market." (Reporting by Eric Onstad, editing by Will Waterman)