BEIRUT (AP) ― Syria’s wounded interior minister cut short his treatment at a Beirut hospital Wednesday and returned home for fear of being arrested by Lebanese authorities, while Syria’s chief of military police defected to the opposition, becoming one of the highest-ranking officers to switch sides.

The twin developments reflected the deepening isolation of Syrian President Bashar Assad’s government, which has suffered a number of setbacks on the battlefield as well.

In the latest challenge, rebels launched a massive attack on a military base in the northern province of Idlib after laying siege to it for weeks.

The defector, Maj. Gen. Abdul-Aziz Jassem al-Shallal, becomes one of the most senior members of Assad’s regime to join the opposition during the 21-month-old revolt against his authoritarian rule.

Al-Shallal appeared in a video aired on Arab TV late Tuesday saying that he was casting his lot with “the people’s revolution.”

He said the military “has become a gang for killing and destruction,” and he accused it of “destroying cities and villages and committing massacres against our innocent people who came out to demand freedom.”

Meanwhile, Interior Minister Mohammed al-Shaar, who was wounded in a suicide bombing Dec. 12 in Damascus and was brought to Beirut for treatment a week ago, left the hospital early and flew home to Damascus on a private jet, officials at Beirut’s Rafik Hariri International Airport said.

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 deadly crackdown against protesters in Syria.

Over the past week, some Lebanese officials and individuals had also called for al-Shaar’s arrest for his role in a bloody 1986 assault in the Lebanese city of Tripoli.

In the 1980s, al-Shaar was a top intelligence official in northern Lebanon when Syrian troops stormed Tripoli and crushed a Sunni Muslim group that supported Palestine Liberation Organization chief Yasser Arafat. Hundreds of people were killed in the battles, and since then, many in northern Lebanon have referred to al-Shaar as “the butcher of Tripoli.”

It was a testament to just how internationally isolated Assad’s regime has become that even in Lebanon, a country Syria controlled for decades, Syrian government officials cannot feel at ease.

“Lebanese officials contacted Syrian authorities, and that sped up his departure,” said the security official, adding that a Lebanese medical team is expected to go to Damascus to continue al-Shaar’s treatment there. “If such arrest warrants are issued, Lebanese judicial authorities will have to arrest him, and this could be an embarrassment for the country.”

The airport and security officials spoke on condition of anonymity because they were not authorized to speak to the media.

Lebanon and Syria have a long and bitter history.

Syrian forces moved into Lebanon in 1976 as peacekeepers after the country was swept into a civil war between Christian and Muslim militias. For nearly 30 years that followed, Lebanon lived under Syrian military and political domination. Damascus was eventually forced to withdraw its troops but has maintained considerable influence in Lebanon.

The defection of Syria’s military police chief represented another setback for the Assad government and came as military pressure builds on the regime, with government bases falling to rebel assault near Damascus and elsewhere across the country.

Dozens of generals, along with thousands of ordinary soldiers, have defected since Syria’s crisis began in March 2011. In July, Brig. Gen. Manaf Tlass became the first member of Assad’s inner circle to break ranks and join the opposition during the uprising, which anti-regime activists estimate has led to more than 40,000 deaths.

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 eight children and three women.

Also, 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.