The Youssef case turned into a side spat with Washington after US State Department spokeswoman Victoria Nuland on Tuesday spoke of a "disturbing trend" of growing restrictions on freedom of expression in Egypt, pointing to the questioning of Youssef and the arrest warrants.
"There does not seem to be an evenhanded application of justice here," Nuland added, saying the Egyptian Government has been slow to investigate police brutality or attacks on anti-Morsi protesters and journalists.
The Muslim Brotherhood's Freedom and Justice Party denounced Nuland's comments as "blatant interference" in Egypt's internal affairs.
Morsi's office joined in, criticising the US Embassy in Cairo after it tweeted a link to an episode of The Daily Show, in which host Stewart defended Youssef and criticised Morsi, saying it was undemocratic to prosecute the Egyptian comic.
Replying to the embassy on Twitter, the presidency wrote, "It's inappropriate for a diplomatic mission to engage in such negative political propaganda."
US Secretary of State John Kerry widened the criticism, warning that Egypt is at a "tipping point". He told reporters yesterday, "It is our hope that there is still time to be able to turn the corner. Recent arrests, the violence in the streets, the lack of inclusivity with respect to the opposition - in public ways to make a difference to the people of Egypt - are all of concern today."
Kerry added that the US was not supporting one man or one party of Egyptians; rather, "the dreams that they have tried to put into reality through their election and through their faith in the democratic process".
Egypt's top prosecutor, a Morsi appointee, asked state security prosecutors to investigate the head of another private TV network, ONTV, a presenter of a show on the network and a phone-in guest to the show over complaints they "disturbed public security" and insulted the judiciary, the state daily Al-Ahram and the Committee to Protect Journalists said.
The complaint was prompted when the guest, Shaimaa Abulkhair, a consultant with the New York-based CPJ, criticised the case against Youssef.
Morsi's office issued a statement denying that it was behind the prosecution's moves, noting that the prosecution is independent.
"The presidency underlines its complete respect for freedom of the expression and the press," the statement said. "All citizens have the right to expression without the restrictions that existed before the revolution" while "respecting the law".
Information Minister Abdel-Moneim Abdel-Maqsoud said the complaints against Youssef's show came from private citizens concerned over the prestige of Egypt's first freely elected President.
Youssef denies the charges of contempt for religion.
"Islam is a wonderful religion, it's a great and peaceful religion," Youssef, a Muslim himself, told CNN this week. "There are some people who claim to be the sole [representatives] of Islam; they are actually giving a bad image, and they're basically insulting the image of Islam."
- AP
