Christians in China are being thrown in jail for gathering to worship or possessing religious literature, according the U.S.-based China Aid.
Bob Fu, who leads the human rights watchdog group, said officials have also pulled crosses off more than 60 churches.
Fu told a congressional subcommittee on Thursday the actions are part of a crackdown on religion.
Robert George, chairman of the U.S. Commission on International Religious Freedom, said there won't be any progress toward democratization and true respect for human rights in China, "until we address the religious freedom violations."
George also said the Obama administration should add Pakistan and Syria to a list of the worst offenders of religious freedom.
Additionally, the Commission also asked the State Department to add eight more nations to the list of "Countries of Particular Concern." Those countries are Egypt, Iraq, Nigeria, Tajikistan, Turkmenistan, Vietnam, Pakistan, and Syria.