Official: Syrian rebels brace for showdown in Aleppo

STORY HIGHLIGHTS

• NEW: Two senior diplomats have defected, the opposition Syrian National Council says
• Rebel troops prepare to face government reinforcements in Aleppo
• Turkey says it is closing all border gates with Syria on Wednesday
• Opposition group: At least 50 people are killed Wednesday

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(CNN) -- Leaders of Syrian rebel forces ordered their fighters to attack hundreds of government troops heading toward Aleppo, the country's largest city, a Free Syrian Army official told CNN Wednesday.

The Syrian regime withdrew about 2,000 fully equipped troops, along with their tanks and artillery, from Idlib and sent them to Aleppo, about 40 miles away, the official said.

As the commercial hub of Syria, Aleppo is a crucial city in the country's 16-month conflict. If rebels eventually gain control of the city it would mark a pivotal point in the Syrian crisis and deal a heavy blow to President Bashar al-Assad's financial ties.

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Across Syria, at least 50 people were killed in fresh violence Wednesday, opposition activists said. The dead included six people in Aleppo and six children, the Local Coordination Committees of Syria said.

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Rebel forces have been trying to wrest control of Aleppo from government forces.

"There is random shelling of the eastern portion of the city as the Syrian Army is trying to force out the FSA (Free Syrian Army). They are hitting civilian homes over and over," one activist told CNN via Skype Tuesday.

CNN's Ivan Watson, who is inside Syria, said he had noticed the rebels had become better armed in the past few months. While they only had shotguns at one point, they now have rocket-propelled grenades and assault rifles, he said.

The increased firepower has helped the rebels successfully attack armored vehicles and forced some Syrian forces to resupply by helicopter.

Watson said that in the village he was in, hundreds of rebels had loaded up with ammunition this week and headed to fight in Aleppo.

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Both Aleppo and the capital city of Damascus have been al-Assad strongholds.

On Tuesday, state-run media reported that regime troops had regained control of neighborhoods in Damascus, where rebels fought al-Assad's forces last week.

Alex Thomson, a journalist for CNN British affiliate ITN, confirmed the developments from Damascus.

"It is quite clear that the regime has just had, in Damascus, the biggest boost to its morale in 16 months of violent civil war," Thomson wrote. "This is a comprehensive victory of the Assad regime in its own backyard and capital."

In what may be a blow to the regime, however, the opposition Syrian National Council said Wednesday that two senior Syrian diplomats were the latest to defect.

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One is the Syrian ambassador to the United Arab Emirates, Abdullatif Al Dabbagh, SNC spokesman George Sabra said.

The second is Al Dabbagh's wife, who is also the Syrian envoy to Cyprus, Lamia Al Harriri. She defected to Qatar, SNC member Najy Tayyarah told CNN. She is also the niece of Syrian Vice President Farouq Al Sharea.

Al Dabbagh had helped a lot of Syrians in need, Tayyarah said from Istanbul.

Meanwhile, Turkey's customs and trade minister said "all border gates with Syria will be closed" Wednesday, Turkish state-run TV reported. A government statement was expected later in the day.

Thousands of Syrians have fled to Turkey in recent months to escape violence in their country, but the refugees generally cross from fields through the border fence, not the border gates.

Video: Fighting breaks out of Syria border gate

The chaos in Syria took an ominous turn this week after a Syrian official discussed his country's weapons of mass destruction.

Jihad Makdissi, Syria's Foreign Ministry spokesman, told reporters Monday that "any stocks of WMD or any unconventional weapon that the Syrian Arab Republic possesses would never be used against civilians or against the Syrian people during this crisis at any circumstances, no matter how the crisis would evolve.

"All the stocks of these weapons that the Syrian Arab Republic possesses are monitored and guarded by the Syrian Army," Makdissi added. He further said that the "weapons are meant to be used only and strictly in the event of external aggression against the Syrian Arab Republic."