Syrian rebels took control of all border crossings between Iraq and Syria on Thursday, Baghdad's deputy interior minister told Agence France Presse, as a rights group said rebels also seized a crossing on the border with Turkey.

"All the border points between Iraq and Syria are under the control of the Free Syrian Army," Adnan al-Assadi told AFP by telephone.

Regime troops stormed a Damascus district with tanks on Thursday for the first time, five days on from the outbreak of fierce clashes in the capital, the Syrian Observatory for Human Rights said.

"The army stormed the Qaboon district with a large number of tanks," the Observatory's Rami Abdel Rahman told Agence France Presse. "This is the first time that tanks enter a Damascus district."

Syrian state television broadcast images on Thursday of President Bashar Assad in a meeting with the new defense minister, Fahd al-Freij.

This was the first public sighting of Assad since a bomb attack in Damascus on Wednesday killed three top regime officials, including Freij's predecessor, Daoud Rajha.

The EU is preparing to freeze the assets of 26 Syrians close to President Bashar Assad while readying plans to board vessels and planes suspected of transporting arms for his regime, diplomats said Thursday.

The diplomats told Agence France Presse that foreign ministers from the 27-nation bloc were likely to agree at talks on Monday to inspect planes and ships believed to be carrying arms or goods used by the Damascus regime to put down protests.

Russia and China on Thursday vetoed a U.N. Security Council resolution that would threaten sanctions against Syria's President Bashar Assad if he does not end the use of heavy weapons.

The third Russia-China veto in nine months opened up an acrimonious battle at the 15-nation council over who is to blame for the world powers' failure to get international action to halt the Syria conflict.

Syrian President Bashar Assad's mother and sister have gone to Tartus province for the funeral of his brother-in-law Assef Shawkat who was killed in Wednesday's Damascus bomb, a security source told Agence France Presse.

"Anissa Assad, the widow of (ex-president) Hafez al-Assad and her daughter Bushra traveled on Wednesday evening along with several women from their entourage to Latakia and they then made their way to Tartus," the source said.

Syria's alliance with Iran and Hizbullah took "a severe blow" after a deadly rebel attack on Damascus killed three top security chiefs, Israeli Defense Minister Ehud Barak said Thursday.

"The blow is a severe one," said Barak on a tour of the Israeli-occupied Golan Heights, a day after a blast tore through Syria's national security headquarters, killing the defense minister and two other top officials close to President Bashar Assad.

A bomb attack that killed three top security chiefs in Damascus marks "the beginning of the end of the regime" of President Bashar Assad, an opposition spokesman said on Thursday.

"We see that what happened (on Wednesday) is a sign of the beginning of the end of the regime," Syrian National Council spokesman George Sabra told Agence France Presse.

President Abdrabuh Mansour Hadi on Thursday told Tehran to stop meddling in Yemeni affairs after the defense ministry said the authorities had uncovered what it called an Iranian espionage network.

"An Iranian spy network that had been operating in Yemen for seven years under the leadership of a former leader in the Iranian Revolutionary Guards" has been dismantled, the ministry's news website 26sep.net reported late on Wednesday.

The families of three U.S. citizens killed in drone strikes in Yemen last year -- including al-Qaida preacher Anwar al-Awlaqi -- have filed a civil lawsuit against top U.S. officials.

The family members argue that the U.S. government's killing of the three men "violated fundamental rights afforded to all U.S. citizens, including the right not to be deprived of life without due process of law."