WASHINGTON, Oct 29 (Reuters) - The Inter-American Development Bank abruptly postponed a meeting at which its executive directors were expected to vote on nominations for top leadership positions from three smaller countries with far smaller shareholdings in the regional bank.

Argentina and Mexico asked for Wednesday's meeting to be postponed until next week, the IDB press office said. It said there was "strong majority support" for the three nominees from Honduras, Ecuador and Paraguay.

No new date has been published on the bank's website.

Officials in Argentina and Mexico had no immediate comment on the reason for seeking a delay in the board meeting.

Both countries had also opposed the candidacy of Mauricio Claver-Carone, a U.S. citizen and former top adviser to U.S. President Donald Trump, who was elected to the lead Latin America's main financial institution last month.

Claver-Carone had nominated Reina Irene Mejia, chief executive of Citi Honduras, for the No. 2 job at the IDB, along with former Paraguayan finance minister Benigno Lopez to serve as vice president of sectors, and Richard Martinez, Ecuador's former finance minister, as vice president of countries, according to sources familiar with the plans.

No comment was immediately available from Claver-Carone, but he was quoted by the Argentine newspaper La Nacion as saying that only Mexico and Argentina were seeking to push off the vote, and the bank should focus on its main job of lending. (Reporting by Andrea Shalal in Washington, Cassandra Garrison in Buenos Aires and Dave Graham in Mexico City; editing by Jonathan Oatis)