Influential U.S. Senator John McCain declared Wednesday that Syrian President Bashar al-Assad has "lost his legitimacy" and called for U.N. sanctions to force him to halt attacks on his people.

But McCain told Agence France Presse he could not see any opening for U.S. military action to topple the Syrian regime, and regretted that Assad was not yet facing an armed revolt like the one fighting to oust Libya's Moammar Gadhafi.

Syria bolstered its troops Tuesday in the flashpoint town of Daraa as a rights group appealed for U.N. intervention in a bloody crackdown it said has killed 400 people since mid-March.

As the Daraa crackdown raged into a second day, Britain said it was working with its partners to send a "strong signal" to Damascus while France and Italy denounced the "unacceptable" situation in Syria.

Italy and France called for an end to the "violent repression" against peaceful protests in Syria on Tuesday, with French President Nicolas Sarkozy saying the situation was "unacceptable".

"We issue a strong call on the authorities in Damascus to end the violent repression against what are peaceful demonstrations," Berlusconi said to a news conference following the summit.

Progressive Socialist Party leader MP Walid Jumblat has urged Syrian President Bashar al-Assad to "continue implementing his previous resolutions on protecting the right to peaceful protest" in unrest-hit Syria.

"As Syria's friend and ally … I urge President Assad to continue implementing his previous resolutions on protecting the right to peaceful protest and expression and to quickly launch a broad dialogue with the various political, syndical, social and economic sectors and the representatives of the civil society to discuss the means of overcoming this critical political period," Jumblat said in his weekly column in his party's mouthpiece Al-Anbaa newspaper.

The United States is considering targeted sanctions against Syrian officials to respond to "completely deplorable" violence used by Damascus's forces to crush dissent, an official said Monday.

Signs of a more muscular U.S. response to violence in Syria followed an assault by Syrian troops backed by tanks in the flashpoint town of Daraa, which killed at least 25 people, as a building crackdown reached new heights.

Syrian troops backed by tanks stormed the flashpoint town of Daraa on Monday killing at least 25 people, witnesses said, as a leading rights activist accused Damascus of opting for a "military solution" to crush dissent.

Troops also launched assaults on the towns of Douma and al-Muadamiyah near Damascus, witnesses said, as the head of the U.N. human rights agency slammed what she said was the Syrian security forces' disregard for human life.

Security forces raided homes across Syria, arresting regime opponents, as funerals were held on Sunday for protesters and mourners killed in a bloody crackdown which activists said cost 120 lives.

Despite a relative lull, security forces killed three more people in the Mediterranean town of Jableh, near the port city of Latakia, Facebook page The Syrian Revolution 2011, a driving force behind the protests, reported.

More than 70 people were killed by security forces during massive demonstrations on Friday across Syria, in one of the bloodiest days since pro-democracy protests erupted in mid-March, according to activists and human rights groups.

"The Syrian security forces committed massacres in several towns and regions today, so far killing 72 people and wounding hundreds," said the London-based Syrian Human Rights Committee in a statement received by Agence France Presse.

Syrian President Bashar al-Assad signed a decree to lift almost five decades of draconian emergency rule on Thursday, as a protest movement that has rocked his regime called further demonstrations.

Assad, who has been in power since he replaced his father 11 years ago, issued the order to scrap the state of emergency along with separate decrees to abolish the state security court and to allow citizens to protest peacefully.

Britain on Wednesday urged its nationals to leave Syria amid escalating unrest in the country against the regime of President Bashar al-Assad.

The Foreign Office said Britons should leave the country on commercial flights while airports remained open.