U.N. chief Ban Ki-moon on Wednesday urged the world "to stop the slaughter in Syria" as dozens of international observers pulled out from the country.

"I make a plea to the world: 'Do not delay... Act now to stop the slaughter in Syria'," the U.N. secretary-general told parliament in Bosnia, the Balkans country that suffered a genocide in Srebrenica in 1995.

Amnesty International warned on Wednesday about disturbing reports of "summary executions" by Syrian troops and rebels, calling them "serious violations of international law."

In a statement, the rights watchdog cited reports from media and local activists on instances in which both Syrian government troops and rebel forces have carried out summary killings.

Two alleged anti-regime activists in Sudan face up to 10 years' prison after a judge charged them on Wednesday in a terrorism-linked conspiracy over Arab Spring-style discontent sparked by inflation.

Rudwan Daoud and Ahmed Ali each face several accusations but the most serious is involvement with a terrorist or criminal organization, their lawyer Khaled Awad said outside the court.

Human rights groups filed a complaint in Paris Wednesday to urge the judiciary to probe the alleged involvement of French firm Qosmos in supplying Syria's regime with surveillance equipment.

While France condemns President Bashar Assad's violent crackdown, it is vital that full information be released "on the involvement of French companies in supplying surveillance equipment to the Syrian regime," said Patrick Baudouin of the International Federation for Human Rights (FIDH).

Police in Bangladesh said Wednesday they had arrested four people over the mugging death of a Saudi Arabian diplomat in the capital in March.

Khalaf al-Ali, 45, the head of Saudi citizen affairs at the embassy in Dhaka, was shot while taking a late-night walk near his home in the city's Gulshan area. He was rushed to a local hospital where he died three hours later.

Turkey's top brass held talks Wednesday about the activities of Kurdish rebels in Syria, after press reports that they were in control of several northern areas of the conflict-torn nation.

"The latest developments in Syria, the activities of the terrorist separatist group in our country and in neighboring countries were discussed at the meeting," Prime Minister Recep Tayyip Erdogan's office said.

About 300 people fled from Syria into Turkey overnight, amid guarantees by Ankara to keep the border open to refugees, the U.N.'s refugee agency said on Wednesday.

"I can confirm we not only have assurances from the Turkish authorities that borders remain open for Syrians fleeing the violence, but also we know that around 300 people crossed last night," said Sybella Wilkes, spokeswoman for the U.N.'s High Commissioner for Refugees.

More than 100 Palestinian families have returned to Gaza over the past week after fleeing spiraling violence in war-torn Syria, a Palestinian NGO said on Wednesday.

According to Hamza Abu Shanab, who heads the Palestinian Assembly for Supporting the Syrian Revolution, the families have begun crossing through the Rafah crossing from Egypt over the past week.

Russia on Wednesday lashed out at the United States for backing the armed opposition to the Syrian regime, saying Washington's failure to condemn the July 18 blast that killed top security officials meant it was justifying terror.

"This is quite an awful position, I cannot even find the words to make clear how we feel," Lavrov told reporters. "This is directly justifying terrorism. How can this be understood?"

Syrian Ambassador to the United Arab Emirates Abdul-Latif al-Dabbagh has defected, al-Jazeera TV reported Wednesday.

The Doha based television said that Dabbagh defected but it did not say where he was.