Two Yemeni policemen and a protester were killed in clashes Wednesday in the country's main southern city of Aden, a security official and medics told Agence France Presse.

"Two Yemeni policemen were killed in a clash between security forces and protesters," the security official said.

Five EU countries are summoning Syria's ambassadors over its violent crackdown on protestors, France said Wednesday, saying it had been joined in the move by Britain, Germany, Italy and Spain.

Foreign ministry spokesman Bernard Valero said Foreign Minister Alain Juppe's chief of staff met with Syrian ambassador Lamia Shakkur on Tuesday "as part of a coordinated move with Britain, Germany, Spain and Italy".

Al-Qaida gunmen killed two soldiers and wounded three others on Wednesday in Yemen's restive southern province of Abyan, a security official told Agence France Presse.

"Gunmen attacked the soldiers with rocket-propelled grenades, killing two and wounding three others in the town of Zinjibar," the capital of Abyan, the official said, adding the attackers then fled.

Libyan rebels appear to be gaining ground against Moammar Gadhafi, the British defense minister said, despite a deadly attack on Misrata port by the Libyan strongman's forces.

"We've seen some momentum gained in the last few days. We've seen some progress made in Misrata. And it's very clear that the regime is on the back foot," British Defense Secretary Liam Fox said on Tuesday.

U.N. leader Ban Ki-moon and western nations expressed growing alarm on Tuesday at the deadly clampdown in Syria, but the U.N. Security Council made little headway in efforts to agree to condemn the violence.

Syria's U.N. envoy pleaded for international understanding for President Bashar Assad, but the U.S. ambassador accused Assad of "disingenuously blaming outsiders" while seeking Iran's help to put down protests.

An explosion rocked a natural gas terminal near Egypt's border with Israel on Wednesday sending flames shooting into the air and forcing the shutdown of the country's export pipeline, said security officials.

It was the second attack in the past month on the al-Sabil terminal near the town of El-Arish just 50 kilometers from the border with Israel. On March 27 gunmen planted explosives at the terminal, that failed to detonate.

Syria bolstered its troops Tuesday in the flashpoint town of Daraa as a rights group appealed for U.N. intervention in a bloody crackdown it said has killed 400 people since mid-March.

As the Daraa crackdown raged into a second day, Britain said it was working with its partners to send a "strong signal" to Damascus while France and Italy denounced the "unacceptable" situation in Syria.

Egyptian ex-interior minister Habib al-Adly pleaded not guilty as he went on trial in Cairo Tuesday accused of ordering the shooting of demonstrators during protests that toppled the former regime.

Adly and six former aides made a brief appearance in a packed Cairo courthouse before Judge Adel Abdul Salam Gomaa, who postponed the trial until May 21 to allow more time for defense lawyers as well for legal experts acting for families of victims.

Speaker Nabih Berri demanded on Tuesday that the investigation into alleged Lebanese meddling in Syrian affairs should be conducted in a legal framework.

He said during a ceremony commemorating poet Najib Jamaledddine: ““All Lebanese should be keener on Syria’s security and stability than the Syrians themselves.”

Italy and France called for an end to the "violent repression" against peaceful protests in Syria on Tuesday, with French President Nicolas Sarkozy saying the situation was "unacceptable".

"We issue a strong call on the authorities in Damascus to end the violent repression against what are peaceful demonstrations," Berlusconi said to a news conference following the summit.