The managing director of Abu Dhabi Investment Authority (Adia), considered the world's biggest sovereign wealth fund, is missing after a glider plane crash in Morocco, the state news agency Wam said.

Sheikh Ahmed bin Zayed al-Nahayan is a younger brother of the ruler of Abu Dhabi, who is also president of the UAE, but is not immediately in line for succession.

'Sheikh Ahmed bin Zayed al-Nahayan...was in a crash of a glider which was airborne in Morocco. The pilot was rescued and is in good condition. The search for His Highness is still continuing,' Wam said in a statement.

The plane had crashed into a lake, Wam reported.

An Adia spokesman declined to comment.

Sheikh Ahmed was No. 27 on Forbes list of the world's most powerful people last year and is in his early 40s. The magazine described him as 'elusive' and he rarely gives interviews.

The sovereign wealth fund, formed in 1976, is believed to have assets of around $500-$700 billion, and range from Citigroup bonds to a stake in Britain's Gatwick airport to residential property in major cities.

In an interview in January, Sheikh Ahmed said the wealth fund was refining its investment approach and might consider a larger investment than its rarely exceeded 5 per cent stakes.

'The rumours that circulate occasionally about Adia planning takeover bids or looking to buy controlling stakes in one company or another are invariably a case of mistaken identity,' he said in the interview published in German business daily Handelsblatt. – Reuters