House GOP leaders are warning Treasury Secretary Henry Paulson and Federal Reserve Chairman Ben Bernanke against coming back to Congress for the other half of the $700 billion in bailout money without first explaining how current funds are being spent.

Minority Leader John Boehner (R-Ohio) and other top Republicans on Wednesday sent a letter to the two financial administrators calling for more information on how the first half of the bailout money is being used. The leaders said the government has “burned through” nearly $350 billion of the funds, and “yet little is understood about how these investments are contributing to the nation’s economic recovery.”

The leaders’ missive cites one incident in which the lawmakers say it took Paulson more than a month to respond to their questions over the use of the money for executive bonuses and bank acquisitions by other banks.

“Such opaqueness is unacceptable, particularly if it is your intention to ask Congress to release the remaining $350 billion in taxpayer funds that were conditionally authorized by Congress this fall,” the leaders wrote.

The GOP leaders call on Paulson and Bernanke to explain how they plan to transition the government out of the private financial sector. They also ask how the two officials will bring more transparency to the bailout process and how they will maximize the effectiveness of the additional $350 billion.