Lebanon has nominated investment banker Ziad Hayek to be head of the World Bank, the first challenge to President Donald Trump's pick to lead the development lender.

The Middle Eastern nation submitted the nomination in a letter to the bank's executive board, Hayek said on Twitter, also posting a copy of the document. He is the sole challenger so far to senior Treasury official David Malpass, who was nominated this month by President Donald Trump.

Under an informal trans-Atlantic custom, the president of the World Bank has always been an American, while the managing director of the International Monetary Fund has always been European. The board has said it will pick the next president based on merit, but some experts are calling for a non-American to be chosen in recognition of the growing clout of emerging markets.

The bank's executive board, which represents its 189 member nations, will have the final say. It has given nations until March 14 to put forward candidates and says it will publish a shortlist of up to three contenders, with the aim of naming the next president by mid-April.

Hayek is secretary general of the high council for privatization and private-public partnerships in Lebanon, where he has been working on reforming the country's power and telecommunication industries. He was previously chief executive of investment bank Lonbridge Associates, a consultant to the State Department and a member of the Council on Foreign Relations.