NEW YORK, Feb 7 (Reuters) - A federal judge on Tuesday rejected a proposal to modify Sam Bankman-Fried's bail conditions, despite an agreement between the FTX cryptocurrency exchange founder and prosecutors to address potential witness tampering concerns. Bankman-Fried, 30, has been free on $250 million bond and living in Palo Alto, California, with his parents, who guaranteed the bond, since pleading not guilty to looting billions of dollars from the now-bankrupt FTX. Separately, prosecutors on Tuesday asked another judge to put on hold Securities and Exchange Commission and Commodity Futures Trading Commission civil lawsuits against Bankman-Fried until the criminal case ended