Israeli police deployed in force in Jerusalem's Old City after limiting access to the al-Aqsa mosque compound ahead of the first Friday prayers during Ramadan.

"More than 2,000 police and border guards were deployed in Jerusalem," said a police spokesman, adding access was blocked to the esplanade for Muslim men under the age of 45.

The Obama administration sent its ambassador back to Damascus on Thursday as it incrementally turned up the heat on Syrian President Bashar Assad with tougher rhetoric and new sanctions.

The White House said Assad's deadly crackdown on protesters had put Syria and the Middle East on a "very dangerous path," as Washington extended a raft of recent sanctions to include a businessman close to Assad and his family.

NATO warplanes bombed the Libyan capital early Friday, state television said, as Moammar Gadhafi's regime accused rebels of sabotaging a key pipeline feeding the country's sole functioning refinery.

About 10 loud explosions rocked the city around 1:30 am (11:30 GMT), an Agence France Presse journalist said.

The United States on Thursday stepped up the pressure on Syria over its crackdown on pro-democracy protesters, imposing sanctions on a businessman close to President Bashar al-Assad and his family.

The move freezes the U.S. assets of Mohammed Hamsho and his company, Hamsho International Group, and prohibits U.S. entities from engaging in any business dealings with them, the Treasury Department said in a statement.

At least 109 people were killed on Thursday in and around the Syrian flashpoint protest city of Hama, CNN quoted a global activist group as saying.

"The brutality continues in Hama on the fourth day of Ramadan. Communication with the city and surrounding area is very difficult as the electricity supply has been cut off," the Avaaz non-governmental organization said.

Field Marshal Hussein Tantawi, Egypt's military ruler, will most likely testify in the trial of former president Hosni Mubarak if summoned after a request by the defense, a security official said Thursday.

Fareed al-Deeb, who represented the fallen dictator at his murder trial, asked the judge in its first session on Wednesday to summon Tantawi and military chief of staff Sami Enan along with some 1,600 witnesses.

The United States warned Thursday that President Bashar al-Assad had put Syria and the Middle East on a "very dangerous path," again toughening rhetoric on a crackdown by Damascus.

Washington appears to be moving towards a first direct call for Assad to go, a step it has so far resisted, and is preparing a new round of sanctions against his regime after an escalation of violence in the revolt hub of Hama.

EU foreign policy chief Catherine Ashton on Thursday dubbed Syria's multi-party reform offer "a step in the right direction" but on condition it be put into effect.

"We are still waiting for previously announced reforms to be implemented," Ashton said in a statement issued after President Bashar al-Assad issued a decree allowing opposition political parties.

Syrian dissidents and activists said Thursday President Bashar al-Assad's decision to allow opposition political parties was a political ploy, and that constitutional change is the only way to democracy.

"The regime is not serious about transforming the country from a dominant party into democracy and pluralism. Instead, it is trying to carry out some cosmetic work to improve its image," Anwar al-Bunni, head of the Syrian Center for Studies and Legal Research, told Agence France Presse.

Russian President Dmitry Medvedev on Thursday called the situation in Syria "dramatic" and expressed "enormous concern" over the deadly violence in the country.

"Unfortunately, people die there in large numbers. This arouses enormous concern from us," the Russian leader said in an interview given to Russian media in the southern resort Sochi.