Russia has delivered anti-ship cruise missiles to Syria, the Moscow-based Interfax news agency reported on Thursday, citing an unnamed military source.

“The contract was completely fulfilled, almost ahead of time,” Interfax cited the source as saying of the deal, estimated at $300 million. The source did not say when the deliveries had taken place.

“This weapon allows coverage of the entire coastline of Syria from possible attack from the sea,” the source added.

The deal took place despite the growing pressure on Syrian President Bashar Assad, who has been brutally cracking down on anti-regime protesters.

Russia, along with China, is against any sanctions on Syria. In October, the two countries vetoed a Western-backed UN Security Council resolution condemning Assad’s government.

Reuters reported on Thursday that Moscow has spoken out against further sanctions imposed by Western and Arab League states on Syria, and has defended its right to sell Syria weapons.

The report noted that selling arms to Syria accounted for seven percent of Russia’s total of $10 billion in arms deliveries abroad in 2010.

Meanwhile, the Arab League tightened its sanctions against Syria early Thursday. The Cairo-based regional body added17 high-ranking Syrian officials to a list banning travel to other Arab states. The list now includes Assad's brother, Maher al-Assad, according to the Egyptian MENA state news agency.

Maher al-Assad, considered the second most powerful man in Syria, is commander of the feared Syrian Republican Guard.

Also on the list were Syria's ministers of Defense and the Interior, as well as senior military and intelligence officials and Assad's millionaire cousin, Rami Makhlouf, head of the country's mobile phone network.

The United Nations has estimated that close to 4,000 people have been killed in the developing civil war in Syria, but activists and human rights organizations have claimed the figure to be much higher, at least 4,500 dead.