Ahmed Omar / AP, file

TV host Bassem Youssef addresses attendants at a dinner party in Cairo on Dec. 8. Prosecutors launched an investigation Tuesday against Youssef for allegedly insulting the president.

Egyptian prosecutors launched an investigation Tuesday against a popular television satirist for allegedly insulting the president in the latest case raised by Islamist lawyers against outspoken media personalities.

Lawyer Ramadan Abdel-Hamid Oqsori charged that TV host Bassem Youssef insulted President Mohammed Morsi by putting the leader's image on a pillow and parodying his speeches.

Youssef's case will increase worries about freedom of speech in the post-Hosni Mubarak era, especially when the country's new constitution includes provisions criticized by rights activists for, among other things, forbidding insults.

In a separate case that fuels concern about press freedom, one of Egypt's leading independent newspapers said it was being investigated by the prosecutor following a complaint from the presidency, which accused it of publishing false news.

Egypt votes on its constitution: What's at stake?

Other cases have been brought against media personalities who have criticized the president. Some of the cases have ended with charges being dropped. Morsi's office maintains that the president has nothing to do with legal procedures against media critics.

A local committee of journalists and editors has called for stronger guarantees of press freedoms and a rejection of the current constitution, fearing it allows for jailing journalists under broadly-worded articles regarding media offenses.

Authorities ordered the closure of TV station Al-Fareen last summer after bringing its owner, Tawfiq Okasha, to trial for scathing attacks against Morsi and his Muslim Brotherhood group. Okasha had emerged as one of the most popular TV personalities of post-Mubarak Egypt by railing against the uprising that toppled Mubarak's 29-year rule in February 2011.

PhotoBlog: Egyptian Copts gather before constitution vote

Rise to fame
Youssef, a doctor, catapulted to fame when his video blogs mocking politics received hundreds of thousands of hits shortly after the 2011 uprising that toppled longtime leader Mubarak.

Youssef's program is modeled after Jon Stewart's "The Daily Show," where he has appeared as a guest.

Unlike other local TV presenters, Youssef uses satire to mock fiery comments made by ultraconservative clerics and politicians, garnering him a legion of fans among the country's revolutionaries and liberals.

Egypt's ex-dictator Mubarak to be moved to military hospital

Huge online following
Among his most popular clips are the ones where he pokes fun at the president's speeches and decisions.

While holding a red, furry pillow with Morsi's picture on it, Youssef satirizes Morsi's style of speech.

"He tells us things we never knew," he says, before wordy clips of Morsi going into detail about the day of the week and other basic facts.

Complete World coverage on NBCNews.com

"It's October 6! Tell us when it's Christmas!" Youssef shouts to the camera as the audience erupts in laughter and applause.

Youssef, 38, is one of Egypt's most popular TV presenters with 1.4 million fans on Facebook and nearly 850,000 followers on Twitter, just shy of the president's number of followers.

The Associated Press and Reuters contributed to this report.

More world stories from NBC News:

• Drug-resistant malaria threatens deadly global 'nightmare'
• From alcohol to kites: An A to Z guide to the Islamic Republic of 'Banistan'
• UK police: Attackers dressed as Oompa Loompas beat man
• Vatican launches swipe-card security system
• US sailors sue Japan's TEPCO for post-quake radiation exposure

Follow World News from NBCNews.com on Twitter and Facebook