Russian Foreign Minister Sergei Lavrov warned Friday against foreign intervention in Syria, calling on the Syrian opposition not to seek a repeat of the "Libya scenario".

"We are very worried that the process of reconciliation, the process of the start of dialogue ... is being slowed down by a desire of some participants to attract foreign forces to support their actions," Russian news agencies quoted Lavrov as saying.

Israeli security forces were on high alert on Friday for fear of violence as the Palestinians begin marking the "Nakba" or "catastrophe" which befell them following Israel's establishment in 1948.

"The police are on high alert and we have deployed thousands of police officers in and around Jerusalem, as well as in the north," police spokesman Micky Rosenfeld told Agence France Presse.

Gunmen killed three protesters tearing up posters of President Ali Abdullah Saleh on Thursday, raising to 19 the death toll in 24 hours and prompting Washington to say the time has come for a transfer of power.

Pro-Saleh gunmen on the roof of the ruling party's headquarters in al-Bayda, 210 kilometers southeast of Sanaa, opened fire at demonstrators tearing up posters of Saleh, witnesses and protest organizers said.

U.S. Secretary of State Hillary Clinton on Thursday blasted Syria's use of strength as "a sign of remarkable weakness" at a news conference in the Greenland capital.

Syria's repression of protests "is a sign of remarkable weakness," Clinton told reporters at an Arctic Council meeting, stressing Syria continued with "a brutal crackdown" on demonstrators despite overwhelming international condemnation.

British Prime Minister David Cameron invited on Thursday the Libyan rebel council to open an office in London after talks with its leader Mustafa Abdul Jalil.

It would be the National Transitional Council's first foreign diplomatic mission and a highly symbolic step in the rebels' fight against Libyan leader Moammer Gadhafi, who was shown on television Wednesday for the first time in nearly two weeks.

A blazing row has erupted between President Mahmoud Ahmadinejad and parliament speaker Ali Larijani over the restructuring of ministries, reports said Thursday, in a fresh sign of tension in Iran's ruling conservative camp.

The row comes shortly after an unprecedented rift surfaced between Ahmadinejad and supreme leader Ayatollah Ali Khamenei which saw the president disappear from public life for nearly two weeks.

The European Union may consider extending sanctions against Syria to include President Bashar Assad himself, EU diplomacy chief Catherine Ashton said Thursday.

"President Assad is not on the list but that does not mean the foreign ministers won't return to this subject," Ashton told Austrian Oe1 public radio in an interview broadcast on Thursday.

U.S. President Barack Obama's long-expected speech on turmoil in the Arab world and North Africa could take place as soon as next week, in the aftermath of the death of Osama bin Laden.

Obama's address will focus on the popular uprisings, violence and political change sweeping the region, and also come at a time of deep uncertainty for his hopes of renewing talks between Israel and the Palestinians.

The U.N. agency for Palestinian refugees on Wednesday said it had suspended operations for 50,000 people in central and southern Syria in the face of the persistent violence sweeping the country.

A U.N. Relief and Works Agency spokesman said the organization had stopped providing services in a refugee camp in the central city of Homs, a hub of anti-regime protests, and had also closed down its operations in and around the southern city of Daraa.

Syrian tycoon Rami Makhlouf warned Israel of instability if the regime of his cousin President Bashar Assad falls, vowing to "fight to the end," according to The New York Times.

"If there is no stability here, there's no way there will be stability in Israel," said Makhlouf, who is on a list of 13 Syrian figures subjected to European Union sanctions for their role in violence against protesters opposing Assad's autocratic government.