DUBAI, July 31 (Reuters) - Dubai entrepreneur Mohamed Alabbar has led two investor groups in buying a combined 16.45 percent stake in Dubai-based courier Aramex , part of a plan to build an e-commerce platform across the Arab world, according to a source familiar with the matter.

Alabbar was a lead investor in Boson Ventures Corporation, which purchased the entire 9.9 percent share that Aramex founder Fadi Ghandour held in the company through Levant Logistics Holdings, the source said.

Ghandour sold the stake to Cayman Islands-registered Boson, it was announced earlier on Sunday in a bourse filing that did not give a value of the sale or elaborate further.

Alabbar was also a lead investor in Jaona Investment, which acquired a 6.55 percent stake in Aramex, according to a bourse statement on Thursday.

The other investors in the two groups were Gulf-based, the source said, speaking on condition of anonymity due to the sensitivity of the matter.

Alabbar is chairman of Emaar Properties , the Dubai government-linked builder of the world's tallest building.

(Reporting by Tom Arnold; Editing by David French) ((Tom.Arnold@thomsonreuters.com; +97144536265; Reuters Messaging: tom.arnold.thomsonreuters.com@reuters.net))