Egyptian prosecutors summoned former President Hosni Mubarak for questioning and arrested former Prime Minister Ahmed Nazif on Sunday,

Egyptian prosecutors summoned former President Hosni Mubarak for questioning and arrested former Prime Minister Ahmed Nazif on Sunday, following protests by demonstrators demanding legal accountability for the country's fallen officials.

Both moves appeared aimed at mollifying growing public frustration over the sluggish pace with which Egypt's new military leadership has prosecuted former regime officials for alleged financial misdeeds.

The prosecutors' action points to the lingering power of the youth-led protest movement. Nearly two months after Mr. Mubarak yielded power to a high military council, the protesters have shown they are still capable not only of convening in large numbers, but also of wresting further political concessions from the military government.

Mr. Mubarak also chose Sunday to make his first comments to the Egyptian public. In a message recorded Saturday and aired Sunday on the pan-Arab Al Arabiya satellite station, the former ruler pledged to cooperate with prosecutors. He also denied that he or his family have held any bank accounts or "assets" abroad.

"I cannot remain silent in the face of the continual campaigns of defamation and false accusations that aim at ruining the reputation and integrity of my family and me," the former president said in the message. "I have felt great pain—and still do—due to the unfair campaigns and unjust accusations to which my family and I have been exposed."

Some protest leaders said they considered the speech an act of defiance by a leader who had stylized himself as a father figure to the Egyptian people.

The speech will do little to assure protesters that the military is making a sincere effort to hold former officials accountable, said Shadi Al Ghazali Harb, a leader in the Revolutionary Youth Coalition, whose members led the three weeks of protests that ousted Mr. Mubarak.

"There's a widespread sense of frustration from the arrogant manner in which he was speaking to us," he said. "We all think that probably he got enough time to mobilize his money and his cash and assets during these past two months for him to be sure that nothing will be held on him, especially abroad," Mr. Al Ghazali Harb added. "That was all under the cover of the military."

The Swiss government said it froze Mr. Mubarak's assets on Feb. 11, the day he stepped down. Egypt's General Prosecutor's Office asked foreign embassies to freeze Mr. Mubarak's assets abroad ten days later.

In one of the largest rallies since Mr. Mubarak stepped down in February, thousands of demonstrators filled Cairo's Tahrir Square Friday to demand former officials be held accountable for perceived widespread corruption. Military police and security officialsforcefully dispersed the crowd at about 3 a.m. on Saturday morning in a confrontation that killed at least one person, according to wire reports. But on Sunday, demonstrators remained in the square.

The violence marked a low point in relations between the protesters, led by young activists, and the armed forces, who have governed Egypt since Mr. Mubarak stepped down on Feb. 11.

A lawyer from the General Prosecutor's Office said the attorney general sent a request Sunday morning to the Ministry of Interior asking that Mr. Mubarak and his sons, Gamal and Alaa, be called to Cairo for questioning.

The former president is believed to have been staying at his home in the resort city of Sharm El Sheikh since he was toppled from power following 18 days of often violent street protests.

The lawyer said it was up to the Ministry of Interior to decide when to summon Mr. Mubarak. The former president is under investigation for allegations of misappropriation of public funds and for allegedly taking kickbacks on deals to import weapons. Prosecutors also will investigate his involvement in violence against protesters during the unrest that led to his ouster, the lawyer said. According to Egypt's Ministry of Health, some 384 people died during the uprising at the hands of police officers, thugs hired by regime officials, and military police.

The lawyer from the prosecutor's office said Mr. Nazif, who was arrested Sunday afternoon, will be detained for questioning for 15 days in connection with a deal to import license plates at marked-up rates from a German company. Mr. Nazif hasn't commented publicly on the allegations.