WASHINGTON - The World Bank said on Wednesday that its president Robert Zoellick would step down when his five-year term ends on June 30.

"I'm honoured to have led such a world class institution with so many talented and exceptional people. Together we have focused on supporting developing countries to navigate crises and adjust to global economic shifts," Zoellick said in a statement released by the Washington-based international lending institution.

The bank said under Zoellick's leadership, it has provided a record 247 billion U.S. dollars to help developing countries boost growth and overcome poverty.

"The bank is now strong, healthy and well positioned for new challenges, and so it is a natural time for me to move on and support new leadership," said Zoellick, adding that he will stay 100 percent focused on being bank president through June 30 and will continue to drive policy and programmes at a heightened tempo.

The board now begins looking for a new president under guidelines directors adopted in 2011 calling for an "open, merit-based and transparent selection" process.

That suggests a break from the informal agreement that dates to the bank's founding almost 68 years ago, under which the bank's president is an American and the head of its sister institution, the International Monetary Fund, is a European.

There is no guarantee that a non-American will be chosen to again head the bank even though China is now the world's second largest economy, and other countries with growing economic clout have been exerting pressure for a change in the U.S.-European arrangement.

The IMF was supposed to follow the same open selection guidelines when it searched for a new managing director last year, but wound up again choosing a European, former French Finance Minister Christine Lagarde.

As Zoellick's term drew to a close, Secretary of State Hillary Rodham Clinton and former Treasury Secretary Lawrence Summers were mentioned as possible successors, though Clinton has said she is not interested in the job.

Zoellick, a Republican appointed by former President George W. Bush, has a good relationship with Treasury Secretary Timothy Geithner and other members of the Obama administration. But analysts who follow the bank and some senior members of its staff said they were not surprised he decided to leave.