Human Rights Watch and the Syrian opposition National Coalition have condemned a gruesome video apparently showing a Syrian rebel fighter cutting out the heart of a regime soldier and eating it.

"International news agencies and social media websites have been circulating a video clip in which a person claiming to be a member of the rebels in Homs performs a horrific and inhumane act," the National Coalition said.

The Iraqi government said on Tuesday that it rejects the entry of Kurdish fighters from Turkey into its territory as a "flagrant violation" of its sovereignty that damages relations with Ankara.

"The Iraqi government confirms its rejection of the withdrawal and the presence of armed men of the Kurdistan Workers' Party (PKK) inside Iraqi territory, which is a flagrant violation of Iraq's sovereignty and independence," a statement from the cabinet said.

A military judge found a U.S. soldier guilty Monday of killing five of his colleagues in Iraq four years ago, a spokesman said, after the defendant made a plea deal to escape a death sentence.

Army Sergeant John Russell was convicted over the May 2009 murders at a clinic for soldiers suffering from war-related stress at Camp Liberty, the largest U.S. base in Iraq.

A German journalist is being held by Syrian forces in the northern battlefield city of Aleppo, a Berlin newspaper reported online Monday, citing his call for help via a mobile phone text message.

Armin Wertz, an Indonesia-based veteran reporter writing for German and Asian media, had entered the conflict-torn country from neighboring Turkey in early May, said the Tagesspiegel daily, for which he works on a freelance basis.

U.N. Secretary General Ban Ki-moon will meet with Russian Foreign Minister Sergei Lavrov on Friday to discuss the Syria crisis, the Russian foreign ministry announced.

"Ban Ki-moon will travel to Russia from May 16 to 19" and will hold talks Friday on "questions of international importance, in particular the crisis in Syria," the ministry said in a statement Monday.

The United States has moved military forces closer to Libya since the Benghazi attack so they will be ready to respond to threats against diplomatic personnel, a Pentagon spokesman said Monday.

"We are prepared to respond if necessary, if conditions deteriorate or if we were called upon," spokesman George Little told reporters.

Iran's Foreign Minister Ali Akbar Salehi warned on Monday of the possibility of Syria breaking up and its conflict spilling across the Middle East unless a political solution can end the bloodshed.

"God forbid, if there was a void, or disintegration, in Syria, this crisis would spill over into all countries in the region," said Salehi, whose country is a close ally of Syrian President Bashar Assad.

Despite a flurry of diplomatic activity aiming to end a war that has claimed more than 80,000 lives, Russia still shows no signs of abandoning its support for the regime of Bashar Assad.

U.S. Secretary of State John Kerry, British Prime Minister David Cameron and now Israeli Prime Minister Benjamin Netanyahu have all found time to meet President Vladimir Putin in the last few days in a new effort to find an international consensus.

A powerful car bomb exploded Monday near a hospital in the Libyan city of Benghazi, killing and wounding dozens in what officials said was the first such attack on civilians since Moammar Gadhafi's ouster.

Officials gave contradicting death tolls, however, as information trickled in about the devastating bombing which destroyed a restaurant and damaged cars and buildings near Al-Jala hospital in the center of Benghazi.

The cousin and former aide of slain Libyan leader Moammar Gadhafi appeared in court on Monday charged with the attempted murder of Egyptian police officers, Agence France Presse reported.

Ahmed Qaddaf al-Dam denied the charges which also included possessing unlicensed weapons and resisting arrest.