Syrian troops shot dead three people and wounded several others on Saturday in the western border town of Tall Kalakh, a witness told Agence France Presse.

"The security forces, who had been encircling Tall Kalakh since the morning, fired machine guns. At least three people were killed and several were wounded," the witness said.

Iranian Foreign Minister Ali Akbar Salehi said on Saturday that he had "no information" on the whereabouts of an American journalist working for al-Jazeera after Damascus said she was sent to Tehran, the official IRNA news agency reported.

"I have no information," Salehi said when asked whether Syria, Iran's main Arab ally, had handed over the journalist.

Libyan leader Moammar Gadhafi on Friday denied reports suggesting that he had been wounded in conflict and said NATO bombs could not reach him, in an audio message broadcast on state television.

"I want to tell you that your bombing will not reach me because millions of Libyans bear me in their heart," said Gadhafi, who also thanked heads of state who had asked about his health after a NATO air strike on Thursday.

Italian Foreign Minister Franco Frattini drew a distinction between Syrian President Bashar al-Assad and Libyan leader Moammer Gadhafi, saying Assad had proposed reforms and played a strong diplomatic role.

"Assad made promises for reforms that he didn't keep. Gadhafi never promised reforms," Frattini said in an interview with Corriere della Sera daily.

President Barack Obama Friday announced his "tireless" envoy to the Middle East, George Mitchell, was resigning, but vowed the U.S. administration remained committed to the faltering peace process.

Describing Mitchell as having taken on "the toughest job imaginable," Obama paid tribute to the veteran diplomat who had "worked grueling hours to advance the interests of the United States and the cause of peace."

Ousted Egyptian president Hosni Mubarak's wife, Suzanne, was moved to an intensive care unit after suffering a heart attack Friday, hours after being ordered detained in a corruption probe, state TV said.

"Suzanne Thabet has been moved to the intensive care unit at Sharm el-Sheikh hospital after suffering a heart attack," state TV said, referring to Egypt's Red Sea resort.

Britain summoned Syria’s ambassador Friday in coordination with other EU nations to warn of fresh sanctions against the regime if it fails to stop a crackdown on protesters, as Turkey's premier said it was premature to say whether President Bashar al-Assad should quit.

In a statement, the Foreign Office said it had "called in the Syrian Ambassador Dr. Sami Khiyami ... to express the UK’s strong concerns about the ongoing situation in Syria."

The office of the U.N. human rights chief said on Friday that it was extremely worried about reports that 700 to 850 people have been killed in Syria's pro-democracy protests since March.

A spokesman for U.N. High Commissioner for Human Rights Navi Pillay again urged Syrian authorities to halt its bid to "silence opponents".

Thousands of people rallied in Cairo's Tahrir Square on Friday calling for unity and the rule of law to be enforced after attacks on churches, state television reported.

Footage aired from the iconic square, the epicenter of protests that overthrew president Hosni Mubarak in February, showed thousands of protesters waving flags and banners in support of national unity.

At least five people were killed in Syria, activists said, despite an order from President Bashar Assad for security forces not to open fire on protesters and an offer of dialogue.

Friday's bloodshed cast a pall over the government's pledges to forge ahead with reforms in Syria, which has been gripped by two months of deadly protests.