The general who heads Syria's military police has defected and joined the uprising against President Bashar al-Assad's regime, one of the highest walkouts by a serving security chief during the country's 21-month uprising, a pan Arab TV station reported today.

Maj.-Gen. Abdul-Aziz Jassem al-Shallal appeared in a video aired on Al Arabiya TV late Tuesday saying he is joining "the people's revolution."

Al-Shallal's reported defection comes as military pressure builds on the regime, with government bases falling to rebel assault near the capital Damascus and elsewhere across the country.

On Wednesday, the Britain-based Syrian Observatory for Human Rights said government shelling in the northeastern province of Raqqa killed at least 20 people, including women and children.

After word came out of al-Shallal's apparent defection, Syrian Interior Minister Mohammed al-Shaar, wounded in a Damascus bombing, headed home on a private jet after treatment in Beirut, airport officials said, despite calls from some Lebanese to put him on trial for Syrian actions in their country.

Officials at Beirut's Rafik Hariri International Airport said al-Shaar left Beirut and was flying to Damascus. They spoke on condition of anonymity in line with regulations. Al-Shaar was wounded on Dec. 12 when a suicide bomber exploded his vehicle outside the Interior Ministry, killing five and wounding many, including the minister.

The Syrian government denied at first that al-Shaar was wounded. Then it emerged that he was brought to a Beirut hospital last week for treatment. The same minister was wounded when a bomb went off on July 18 during a high-level crisis meeting in Damascus, killing four top officials.

A top Lebanese security official told The Associated Press that al-Shaar was rushed out of Lebanon after authorities there received information that international arrest warrants could be issued against him because of his role in the crackdown against protesters in Syria.

Over the past week, some Lebanese officials and individuals have called for al-Shaar's arrest for his role in a 1986 crackdown in the northern city of Tripoli.

Dozens of generals, thousands of soldiers defected

Dozens of generals have defected since Syria's crisis began in March 2011.

In July, Brig.-Gen. Manaf Tlass was the first member of Assad's inner circle to break ranks and join the opposition. Al-Shallal was one of the most senior members of the inner circle, and held a top post at the time that he left.

He said in the video that the "army has derailed from its basic mission of protecting the people and it has become a gang for killing and destruction." He accused the military of "destroying cities and villages and committing massacres against our innocent people who came out to demand freedom."

Thousands of Syrian soldiers have defected over the past 21 months and many of them are now fighting against government forces. Many have cited attacks on civilians as the reason they switched sides.

The observatory said the shelling in an agricultural area of Raqqa province near the village of Qahtaniyeh killed 20, including eight children, three women and nine others.

An amateur video showed the bodies of a dozen people including children lying in a row inside a room. Some of them had blood on their clothes, while weeping could be heard in the background.Syrian President Bashar al-Assad, right, met with the UN Arab League's deputy to Syria, Lakhdar Brahimi, in Damascus on Monday. Brahimi said the situation in Syria is still worrying after discussing the crisis with Assad. (SANA/Associated Press)

The videos appeared genuine and corresponded to other AP reporting on the events depicted.

Also Wednesday, activists said rebels were attacking the Wadi Deif military base in the northern province of Idlib. The base, which is near the strategic town of Maaret al-Numan, has been under siege for weeks.

The observatory said at least five rebels were killed in the fighting that started after midnight. It added that Syrian army warplanes attacked rebel positions in the areas.

"It is the heaviest fighting in the area in months," said the observatory, which relies on activists throughout Syria.

In October, rebels captured Maaret al-Numan, a town on the highway that links the capital Damascus with Aleppo, Syria's largest city and a major battleground in the civil war since July.

The attack on Wadi Deif comes a day after rebels captured the town of Harem near the Turkish border. The rebels have captured wide areas and military posts in northern Syria over the past weeks.

Envoy to Syria worried about conflict

Syria's crisis began with protests demanding reforms but later turned into a civil war. Anti-regime activists estimate more than 40,000 have died in the past 21 months.

Members of the Free Syrian Army walk among damaged structures in Idlib, where fighting has been fierce over the holidays. (Abdalghne Karoof/Reuters)

In neighbouring Lebanon, airport officials in Beirut said Syrian Deputy Foreign Minister Faisal Mekdad and Assistant Foreign Minister Ahmad Arnous flew early Wednesday to Moscow. Their visit comes two days after Assad met in Damascus with international envoy to Syria Lakhdar Brahimi.

Brahimi, who is scheduled to go to Moscow before the end of the month, said after the talks Monday that the situation was "worrying" and gave no indication of progress toward a negotiated solution for the civil war.

Brahimi is still in Syria and met Tuesday with representatives of the opposition National Co-ordination Body, state-run news agency SANA said. Head of the group Hassan Abdul-Azim said Brahimi briefed them on the efforts he is exerting to reach an "international consensus, especially between Russia and the United Stated to reach a solution."

Rajaa al-Naser, NCB's spokesman, said his group has put forward proposals adding that there would be no exit but through halting violence and forming a "transitional government with full prerogatives."

Brahimi is expected to arrive in Moscow on Saturday for talks on the Syrian crisis, the ITAR-Tass news agency quoted a senior Russian diplomat as saying Wednesday.

Russia has used its veto right alongside China at the UN Security Council to protect its old ally from international sanctions over a civil war that has killed more than 40,000, but it has increasingly sought to distance itself from Assad.

Foreign Minister Sergey Lavrov said last week that Moscow would welcome any country's offer of a safe haven to Assad, but has no intention of giving him shelter if he steps down.

At the same time, Moscow has given no indication that it could end its firm opposition to international sanctions against Assad and calls for him to step down.