The Syrian Observatory for Human Rights said the army of President Bashar Assad was aiming to take back control of the "Brigade 80" base outside of Aleppo, which rebels had seized on Wednesday.

The base had previously been used by the army to guard both aviation facilities. Its rebel seizure on Wednesday left at least 150 dead from both sides, the observatory said.

The observatory said on Friday that army forces still controlled Aleppo's civilian airport and the Nairab military airfield and had shelled outlying rebel positions. The rebels, in turn, had fired homemade rockets at Nairab.

Rebels target aviation

Activists quoted by the French news agency AFP said the rebel Free Syrian Army decided several weeks ago to switch emphasis from Aleppo's inner-city military stalemate to air hubs. If seized, they could put out of action warplanes which Assad's regime has used for months to bomb rebel-held areas.

The observatory also listed fighting in several suburbs of Damascus, around the eastern city of Deir el-Zour and what it said was a government bombardment of the northern Syrian town of Khan Sheikhoun. Eleven people, including a child, had been killed, it said.

AFP also reported what appeared to be reprisal kidnappings involving dozens of civilians in minibuses in the northwestern province of Idlib. Those involved came from villages of both Shiites and Sunnis.

Rebels are largely Sunni while the president's clan belongs to an offshoot of Shiite Islam.

Turkey fires back

Turkey's state-run news agency Anatolia said a shell fired from neighboring Syria prompted Turkish artillery to fire back on Friday. The initial shell fell near the Turkish town of Yayladag in Hatay province without causing injuries.

Finnish customs officials meanwhile say they have intercepted a shipping container with spare parts for Russian-made tanks. It originated in Russia and was bound for Syria, they said. The crew of the Finnlines vessel searched in Helsinki port had been questioned.

Russia is a long-standing ally of Assad and supplied nearly $1 billion worth of arms to Syria in 2011. The United Nations estimates that almost 70,000 people have been killed in Syria's 23-month conflict.

ipj/kms (AFP, AP, dpa, Reuters)