Syrian opposition groups insisted on regime change as they met in Turkey on Wednesday, a day after President Bashar Assad decreed an amnesty for political prisoners following two months of bloodshed.

The three-day gathering -- titled "Conference for Change in Syria" -- opened with the Syrian national anthem and a minute of silence for "the martyrs" killed in bloody crackdowns on street protests simmering in Syria since March.

A U.N. panel on Wednesday accused Libyan leader Moammar Gadhafi's regime of carrying out systematic attacks on the population, saying that it committed not only war crimes but also crimes against humanity.

While it found fewer reports of violations by the opposition, the commission of inquiry set up by the U.N. Human Rights Council also found that rebel forces committed acts that constituted war crimes.

Libyan Oil Minister Shukri Ghanem announced Wednesday in Italy that he had resigned and left Libya to join the uprising against Moammar Gadhafi "to fight for a democratic country."

"I can't work in this situation so I have left my country and my job to join the choice made by young Libyans to fight for a democratic country," he told journalists, following weeks of rumors and denials about his defection.

Syrian President Bashar al-Assad Wednesday launched a "national dialogue" while freeing hundreds of political prisoners in an amnesty opposition groups and Washington say does not go far enough.

State television said Assad had set up a committee and charged it with "formulating general principles of dialogue that will open the way for the creation of an appropriate climate in which the different elements can express themselves and present their proposals."

Gunbattles raged Wednesday on the streets of Yemen's capital, killing 39 people, witnesses said as a truce between security forces and tribesmen collapsed, residents fled and embassies bolted their doors.

A medic at Jumhuriya hospital said 37 people, most of them combatants, were killed in overnight clashes in Sanaa, while an Agence France Presse photographer said the bodies of two other tribesmen were taken to Al-Ulum hospital during the day.

Britain believes that Syria should be reported to the U.N. Security Council over its alleged illicit nuclear activity, Britain's ambassador to the International Atomic Energy Agency (IAEA) said Wednesday.

In a restricted report circulated to member states last week, the U.N. watchdog said it was "very likely" that a remote desert site in Syria bombed by Israeli planes in 2007 was indeed a covert nuclear reactor, as alleged by the United States.

Ousted Egyptian president Hosni Mubarak and his two sons, Alaa and Gamal, are to face trial on August 3 on charges of ordering the killing of protesters and fraud, a judicial source told Agence France Presse Wednesday.

The trio will be tried by the North Cairo criminal court and the hearing will be presided by Judge Ahmed Rifat, the source said.

The Gulf state of Kuwait withdrew diplomatic staff from its embassy in the Yemeni capital Sanaa on Wednesday because of the security situation, the foreign ministry said.

The Kuwaiti diplomats "have left Sanaa this morning (Wednesday) due to the tense security situation" in Yemen, the official KUNA news agency reported, citing an official source at the foreign ministry.

NATO allies agreed Wednesday to extend its military campaign in Libya for another 90 days until late September, the alliance said.

"NATO and partners have just decided to extend our mission for Libya for another 90 days," said NATO Secretary General Anders Fogh Rasmussen.

Syrian opposition activists opened a conference in Turkey on Wednesday to discuss ways of a regime change in their country and draw up a "roadmap" for a peaceful transition.

More than 300 dissidents, mostly exiles representing various opposition and ethnic groups, gathered at a hotel in the Mediterranean resort of Antalya, a day after Syrian President Bashar Assad decreed an amnesty for political prisoners which they dismissed as inadequate.