Security forces killed at least 30 civilians on Tuesday in Syria, among them 17 in the eastern protest hub of Deir Ezzor, activists said.

"At least 15 people were killed in different parts of Deir Ezzor which has been raided by tanks and vehicles mounted with machine guns," the Syrian Observatory for Human Rights said, quoting activists at the scene.

Several powerful blasts rocked Libya's capital on Tuesday, as the executive branch of Libya's rebel government was sacked in a political crisis a week after their military chief's assassination.

The explosions in the Fernej district of southwest Tripoli struck at between 1:00 am (23:00 GMT) and 2:00 am, sending flames shooting into the night sky, an Agence France Presse correspondent said.

Gunmen shot dead one policeman and wounded another on Tuesday in Yemen's main southern city of Aden, a police official told Agence France Presse.

"Unidentified gunmen opened fire on two policemen who were coming back from work, and then fled," the official said.

Turkey's foreign minister has left for Damascus to press the Syrian leadership into ending the violent crackdown of the five-month old uprising.

Ahmet Davutoglu's visit on Tuesday comes days after Turkey said its patience with its neighbor was running out. Envoys from India, Brazil and South Africa are also slated to arrive in Damascus on Tuesday to appeal for an end to the violence.

Libya's rebel leader disbanded the entire executive branch of his de-facto government Monday, officials said, in a bid to end a major political crisis caused by the assassination of a top rebel general.

Mustafa Abdul Jalil, chairman of the National Transitional Council dismissed several senior officials, including the rebels' finance, defense and information ministers.

The Syrian regime's promises of democratic reforms lack any credibility as long as a violent crackdown on protests in the country continues, Italy's foreign ministry said in a statement on Monday.

"Only an immediate end to violence by Syrian authorities and the start of peaceful dialogue with the opposition and civil society can lend coherence to announcements of reform initiatives or future elections," it said.

Syrian President Bashar al-Assad on Monday appointed a new defense minister, state television reported, amid mounting Arab condemnation of nearly five months of deadly crackdown on dissent.

"President Assad has signed a decree naming General Daoud Rajha as the head of the defense ministry," the television report said.

Hundreds of people demonstrated in central Tunis Monday to demand that members of the toppled Ben Ali regime be stopped from re-entering the political scene or escaping justice for alleged crimes.

The protest, the latest in a series in Tunisia since Zine el Abidine Ben Ali was forced out in January by a popular uprising, came days after courts freed two ministers in the former system who were facing corruption charges.

The head of the 22-member Arab League on Monday urged Syrian authorities to launch a "serious dialogue" with protesters seeking change in the autocratic country.

"What is happening in Syria worries the Arab League and all countries," Nabil al-Arabi told reporters.

EU nations are eyeing new sanctions against Syrian individuals and businesses linked to the ongoing clampdown on dissent by President Bashar al-Assad's regime, EU diplomats said Monday.

The sources, who asked not to be identified, said the European Union was looking at adding to a list of 38 people and businesses already targeted by a an asset freeze and visa ban.