Oren, Alon and Tal Alexander were denied bail in a Manhattan courtroom on Wednesday, after a judge ruled that the three brothers posed both a danger to the community and might flee the country as they awaited trial on federal sex-trafficking charges.

“The weight of the evidence is strong,” said Judge Valerie E. Caproni of Federal District Court after a three-hour hearing in which the brothers’ lawyers sought to undermine the government’s argument for detention, suggesting that the dozens of women who have accused them of assault were concocting stories for profit.