US Secretary of State John Kerry criticized Sudan for sentencing a Christian woman to hang for apostasy, urging Khartoum to repeal its laws banning Muslims from converting.
Meriam Yahia Ibrahim Ishag, who was born to a Muslim father, was sentenced to death on May 15 under Islamic sharia law that has been in place since 1983 and outlaws conversions under pain of death.
"The United States remains deeply concerned about the conviction and continued imprisonment of Ms Meriam Yahia Ibrahim Ishag," Kerry said in a statement.
The top US diplomat said he was "deeply committed" to a better future for Sudan and its people.
"That is one of the reasons we are all so concerned about the travails of Meriam Yahia Ibrahim Ishag," he added.
Ishag was raised an Orthodox Christian, her mother's religion, married a Christian man originally from South Sudan and already had a 20-month-old son before she gave birth in prison on May 27.
Kerry urged Sudanese authorities to allow Ishag, 27, to be reunited with her family.
"I urge the Sudanese judiciary and government to respect Ms Ishag's fundamental right to freedom of religion," he said.
"I also urge Sudan to repeal its laws that are inconsistent with its 2005 Interim Constitution, the Universal Declaration of Human Rights and the International Covenant on Civil and Political Rights.
"Such actions would help to demonstrate to the Sudanese people that their government intends to respect their fundamental freedoms and universal human rights."
The case has embarrassed the Sudanese authorities, which has given contradictory statements about her possible release, raising the ire of Western governments and human rights groups.