By PABLO BACHELET | Miami Herald

Felipe Sixto, from Miami, is under investigation over allegations he misused U.S. grant money to promote Cuban democracy.

An aide to President Bush has resigned in the midst of an investigation by the Justice Department over allegations he misused U.S. grant money intended to promote democracy in Cuba, the White House said Friday.

Felipe Sixto, a Cuban American from Miami, was the special assistant to the president on inter-governmental affairs, dealing with Cuba and other issues.

Sixto was until last summer the chief of staff of Frank Calzón, the head of the Washington-based Center for a Free Cuba. Sixto did not respond to e-mails and calls to his home Friday.

Calzón said he welcomed the investigation by the Justice Department and the U.S. Agency for International Development, which had provided the grants.

Neither Calzón nor the White House revealed how much money was misused but people familiar with the investigation say several hundreds of thousands of dollars could be involved—an embarrassing development coming just weeks ahead of the Bush administration’s roll-out of its 2008 Cuba grant program. White House spokesman Blair Jones said the White House learned of the allegations from Sixto himself as he resigned from his post on March 20.

In 2006, the Government Accountability Office reported that most bids for Cuba grants were awarded without competitive bids and found some abuse.

But the report also found that the grant money had led to large amounts of equipment and literature being distributed to Cuban democracy activists.

Calzón’s Center works with foreign governments and activists in Cuba to raise awareness on human rights abuses. He said it was the Center that initiated an investigation in mid-January when ‘‘an allegation’’ of the misuse of funds emerged.