The Syrian authorities must drop all charges against prominent peace activist Mazen Darwish and two of his colleagues, 19 human rights organisations said on Friday.

Darwish, Hussein Gharir and Hani Zaitani "are facing trial on terrorism charges for their peaceful activism", said the groups, including Human Rights Watch, Reporters Without Borders and Amnesty International.

Hundreds of people marched on Cairo's Tahrir Square on Friday calling for Egypt's Islamist President Mohamed Morsi to resign and demanding early elections, Agence France Presse correspondents and local media reported.

The demonstration was called by a number of opposition groups, including the Al-Dustur party of former U.N. atomic watchdog chief Mohamed ElBaradei and the April 6 movement which spearheaded the 2011 uprising to oust then president Hosni Mubarak.

Visiting German Foreign Minister Guido Westerwelle on Friday reaffirmed his country's friendship for Israel in "challenging times" for the region, as tensions mount over the Syrian conflict.

"I want to underline that in these challenging times Germany stands alongside its Israeli partners," Westerwelle said at the start of talks in Jerusalem with Prime Minister Benjamin Netanyahu, calling his host a "dear friend."

Bombs targeting Sunnis, including two near a mosque and one at a funeral procession, killed 67 people in Iraq on Friday, officials said, after dozens died in two days of attacks on Shiites.

The violence raises the specter of tit-for-tat killings common during the height of sectarian bloodletting in Iraq that killed tens of thousands of people, and comes at a time of simmering tension between the Sunni minority and Shiite majority.

Israeli Justice Minister Tzipi Livni on Friday slammed Russian arms deals with Syria, after US media reported further weapons shipments to the Damascus regime.

Livni's comments also come in the wake of a surprise visit by CIA chief John Brennan to Israel to discuss the situation in Israel's war-torn neighbor.

More than 1.5 million Syrians have fled their conflict-ravaged homeland, the U.N.'s refugee agency said Friday, warning that the real figure could be even higher as the tally only reflected those who register with aid groups.

Dan McNorton, spokesman for the U.N. High Commissioner for Refugees, told reporters that close to 250,000 Syrians were being registered each month.

Turkey has arrested one of the major suspects in the twin car bombings that killed at least 51 people in a city near the Syrian border, the city's governor said on Friday.

"We captured one of the chief actors involved in the incident at 11:40 pm last night," said Celalettin Lekesiz, governor of southeastern Turkey's Hatay city where the bombs went off.

Egyptian police closed the Rafah border crossing with Gaza on Friday in protest at the kidnapping of colleagues in the Sinai peninsula, a security source and witnesses said.

Three policemen and four soldiers were abducted on Thursday by armed men who are demanding the release of a group of prisoners held at a police station in the North Sinai town of El-Arish, official media reported.

The bodies of two Iraqi Shiites killed fighting in neighboring Syria alongside President Bashar Assad's forces arrived home on Friday, providing more evidence that members of Iraq's Shiite majority have joined the war.

The bodies, in coffins wrapped in Iraqi flags, were brought to the southern city of Basra by four-wheel-drive vehicle, an Agence France Presse correspondent reported.

U.N. chief Ban Ki-moon and Russia agreed Friday that a peace conference on Syria should be held "as soon as possible" even as Moscow defied growing global pressure over its arms supplies to the Damascus regime.

Ban met Foreign Minister Sergei Lavrov ahead of talks later Friday with Russian President Vladimir Putin about an impending international meeting on Syria that should include representatives of the two warring parties for the first time.