Abu Dhabi Investment Authority (Adia), considered the world's largest sovereign wealth fund, still sees big risks to the global economy and plans to refine its investment approach to cope with downturns.

In an interview published in German business daily Handelsblatt on Monday, Sheikh Ahmed bin Zayed Al Nahayan, Adia's managing director, also said US treasuries were still the most liquid benchmark, and will remain an important diversification tool.

The sovereign wealth fund, believed to have assets around $500-$700 billion, rarely details its investment strategy or investments.

Sheikh Ahmed -- part of the ruling family of Abu Dhabi, the wealthiest member in the United Arab Emirates' federation -- said Adia would focus on a highly diversified investing strategy and "exercise great caution" before making long-term adjustments in the midst of a major downturn.

"While attention now is on the recovery, we can't lose sight of the many substantial risks that still exist," he said in the transcript of the interview provided to Reuters.

In the wake of the global financial crisis, Sheikh Ahmed said Adia was reviewing its performance. "You can be sure that, like everyone else, we are looking closely to identify areas where strategies perhaps did not work as well as they could have, and will refine our approach where needed."    

Adia has switched its weightings across asset classes to reduce the impact of economic downturns over the past 18 months, he said, adding that its allocation to global equities had averaged 40-60 percent, with 60 percent of that indexed.

Regionally, the wealth fund has its largest allocation in the US, with 35 to 50 percent, followed by Europe at up to 35 percent and Asia at up to 20 percent.

Sheikh Ahmed declined to comment on Adia's dispute with Citigroup over a $7.5 billion investment, reiterating the fund would pursue its legal rights. - Reuters