Poland said it evacuated its embassy staff from Damascus Friday, cutting short its diplomatic work on behalf of the United States which pulled out its own diplomats in February.

Foreign Minister Radoslaw Sikorski "decided to indefinitely close the Polish Republic's embassy in Damascus including the United States section as of July 27," his ministry said in a statement.

Syrian rebels on Friday captured 150 regime troops and militia members in the northern city of Aleppo and the northwestern province of Idlib, the Britain-based Syrian Observatory for Human Rights said.

It reported rebels as saying they had captured 100 regime soldiers and militia members in Aleppo and another 50 in Idlib, citing videos distributed by Syrian activists.

The Red Cross said Friday it will pull some members of its humanitarian team out of conflict-ravaged Syria in the next few days.

"Some of the International Committee of the Red Cross team will move to Beirut in the next two days," said ICRC spokesman Hicham Hassan, adding that 50 international and local staff would remain in Damascus.

The Russian military warned Friday that any attempt by Syrian rebels to attack a Russian military base at the Syrian port of Tartus would be “rebuffed immediately.”

"If the armed Syrian opposition ventures to implement their threat and to attack the Russian naval supplies and maintenance facility, Russia has ample capabilities in the region now to provide an adequate response. We won't recommend hotheads in the Syrian opposition doing that," a source in the Russian General Staff told the Interfax news agency.

The battle between rebels and regime for Syria's second city Aleppo is a crucial fight that could determine the trajectory of the more than 16-month uprising against President Bashar Assad, experts say.

Troops and rebel fighters are massing in and around the city, and al-Watan newspaper, which is close to the regime, pulled no punches describing the fighting in the northern commercial hub.

World powers voiced fears Friday over an imminent all-out assault by President Bashar Assad's forces on Syria's second city Aleppo and called for "maximum pressure" to prevent a new massacre.

France echoed U.S. concerns that Assad was preparing to carry out a slaughter of his own people, and Britain warned that the expected offensive could end in a humanitarian disaster.

Turkey said Friday it would not tolerate the presence of "terrorist" groups such as the outlawed Kurdistan Workers' Party (PKK) or al-Qaida on Syrian soil near the Turkish border.

"Whether it is the PKK or al-Qaida, we will not allow a terrorist organization to set up at our borders," Foreign Minister Ahmet Davutoglu told Turkish television channel Kanal 24.

Two Syrian opposition activists unfurled an enormous rebel flag at the base of the Eiffel Tower in Paris on Friday and were arrested by police.

As a handful of supporters from the France Syria Democracy group rallied below, the two activists climbed scaffolding set up for maintenance works and released the flag, to applause from tourists gathered below.

Italy called on Friday for "maximum pressure" to be exerted on President Bashar Assad to prevent further massacres in Syria, after a sharp escalation in violence there.

"We need everyone to raise the pressure to maximum on Assad to ward off a new massacre," Foreign Minister Giulio Terzi said in a statement.

The U.N. human rights chief voiced alarm Friday at reports of atrocities in Syria and warned that civilians were at "grave risk" amid fears of a major battle in the second city of Aleppo.

"I have been receiving as yet unconfirmed reports of atrocities, including extra-judicial killings and shootings of civilians by snipers, that took place during the recent fighting in various suburbs of Damascus," U.N. High Commissioner for Human Rights Navi Pillay said in a statement.