A top Russian diplomat said on Thursday that the regime of President Bashar Assad is losing "more and more" control of Syria after 21 months of conflict and an opposition victory cannot be ruled out.

The comments by Deputy Foreign Minister Mikhail Bogdanov appear to be the first time a senior Russian official has explicitly acknowledged that the opposition could defeat Assad and take power in Syria.

Syrian Interior Minister Mohammed Ibrahim al-Shaar was wounded in a deadly bomb attack targeting his ministry on Wednesday but his condition is not serious, a security source told Agence France Presse.

"He was wounded in the shoulder when the ceiling fell in his office," the source said on Thursday, speaking on condition of anonymity.

At least 24 civilians, including a large number of children, were killed in two separate car bombings southwest of Damascus on Thursday, state media reported.

Eight people, mostly women and children, were killed by a car bomb in the poor Sunni town of Jdaidet Artuz, state television reported.

The Interpol will not deal with the Syrian arrest warrants against former Prime Minister Saad Hariri, al-Mustaqbal MP Oqab Saqr and Syrian opposition member Louay al-Meqdad in line with its constitution and rules, al-Mustaqbal newspaper reported on Thursday.

According to a memo sent by the Interpol to its offices in the Arab countries, the organization decided not to keep the arrest warrants in its database and will not cooperate with them based on its regulations as “it is strictly forbidden for the organization to undertake any intervention or activities of political, military, religious or racial character.”

The Syrian regime has begun using missiles and barrel bombs against opposition rebels in the past week or so, a top U.S. official said Wednesday, denouncing the increasing use of "vicious weapons."

Amid reports that Scud missiles have been fired, State Department spokeswoman Victoria Nuland said she "was not in a position to confirm types of missiles, simply to say that we're seeing missiles employed now."

The head of the Syrian National Coalition has been invited for talks in Washington following U.S. recognition of the opposition bloc as the legitimate representative of the Syrian people, a senior U.S. envoy said on Wednesday.

"We have extended an invitation to (Ahmed) Moaz al-Khatib and the Coalition leadership to visit Washington at the earliest opportunity," Deputy Secretary of State William Burns said in Morocco, where he was attending a meeting of the Friends of Syria group.

Explosions outside the Syrian interior ministry, including a car bomb, killed seven people and wounded 50 others on Wednesday, a security official said.

Interior Minister Mohammad al-Shaar and other top ranking officials escaped unharmed, state television reported.

Syria accused on Wednesday former Premier Saad Hariri, Mustaqbal MP Oqab Saqr, and Syrian opposition member Louay al-Meqdad of committing terrorist crimes, reported Syria's SANA official news agency.

Damascus' First Attorney-General Mohammed Marwan al-Loji stated: “Failure to bring Hariri, Saqr, and Meqdad to justice is a violation of international law.”

Belgium on Wednesday offered to host an office of Syria's opposition National Coalition in Brussels, headquarters of both the European Union and NATO.

Speaking from Morocco where he was attending a meeting of the Friends of Syria group, Foreign Minister Didier Reynders told the national Belga news agency that "I have proposed to the (Syrian) coalition that it organise a representation in Brussels."

The opposition National Coalition, newly recognized by Washington as the legitimate representative of the Syrian people, on Wednesday urged the U.S. to review its blacklisting of the jihadist Al-Nusra Front.

"The decision to blacklist one of the groups fighting the regime as a terrorist organization must be re-examined," the bloc's leader, Ahmed Moaz al-Khatib, said at a meeting in Morocco of the Friends of Syria group that includes the United States.