Islamic State jihadists blows up ancient Baal Shamin temple in Palmyra
The sanctuary of Baal, pictured in the ancient oasis city of Palmyra, in March 2014 (AFP Photo/Joseph Eid)

Jihadists with the Islamic State group have blown up a famous temple at Syria's ruins of Palmyra, an official said, confirming fears they would destroy more world-class heritage sites.

The destruction of the Baal Shamin temple, considered ancient Palmyra's second-most significant temple, raised concerns for the rest of the UNESCO World Heritage-listed ruins.

It comes only days after IS beheaded the 82-year-old retired chief archaeologist of Palmyra, sparking widespread condemnation.

"Our worst fears are sadly being realised," Syria's antiquities chief Maamoun Abdulkarim told AFP, as he confirmed the temple had been destroyed on Sunday.

Famed for its well-preserved Greco-Roman ruins, Palmyra was seized from government forces in May, prompting concerns IS might destroy it as it has done with heritage sites in parts of Syria and Iraq under its control.

Until Sunday, most of Palmyra's best-known sites had been left intact, though there were reports IS had mined them and the group reportedly destroyed a well-known statue of a lion outside the city's museum.

"Daesh placed a large quantity of explosives in the temple of Baal Shamin today and then blew it up," Abdulkarim said on Sunday.

"The cella (inner area of the temple) was destroyed and the columns around collapsed," he said.

The Syrian Observatory for Human Rights, a Britain-based group that monitors the country's civil war, confirmed the destruction of the temple.

The Observatory said the temple had been destroyed a month ago. The discrepancy could not be immediately explained but information on Syria's civil war is often unclear.

- 'Pearl of the Desert' -

IS captured Palmyra on May 21, sparking international concern about the fate of the heritage site described by UNESCO as of "outstanding universal value".

Baal Shamin was built in 17 AD and expanded under the reign of Roman emperor Hadrian in 130 AD.

Known as the "Pearl of the Desert", Palmyra is an oasis town about 210 kilometres (130 miles) northeast of Damascus.

Its name first appeared on a tablet in the 19th century BC as a stopping point for caravans travelling on the Silk Road and between the Gulf and the Mediterranean.

But it was under the Roman Empire -- beginning in the first century BC and lasting another 400 years -- that Palmyra rose to prominence.

Before the arrival of Christianity in the second century, Palmyra worshipped the Semitic god Bel, whose temple at Palmyra is considered the city's most significant, in triad with the sun god Yarhibol and lunar god Aglibol.

Prior to the outbreak of the Syrian conflict in March 2011, more than 150,000 tourists visited Palmyra every year, admiring its beautiful statues, more than 1,000 columns and formidable necropolis of some 500 tombs.

IS mined the ancient site in June before destroying the Lion Statue of Athena -- a unique piece made of limestone that stood more than three metres high (10 feet) outside a museum.

- Antiquities chief beheaded -

Most of the pieces in the museum were evacuated by antiquities staff before IS arrived, though the group has blown up several historic Muslim graves.

IS's harsh version of Islam considers statues and grave markers to be idolatrous and the group has destroyed antiquities and heritage sites in territory under its control in Syria and Iraq.

IS has also executed hundreds of people in the city and surrounding area, many of them government employees, and infamously used children to shoot dead 25 Syrian government soldiers in Palmyra's ancient amphitheatre.

Among those it has killed was Khaled al-Assaad, Palmyra's antiquities chief for 50 years, who was beheaded last week after refusing to leave the city following the IS takeover.

In neighbouring Iraq, the jihadist group has razed some relics of ancient Mesopotamia and looted others to sell on the black market.

In February, it released a video showing militants using sledgehammers to smash statues in the country's second city Mosul. The group's fighters have also burned thousands of rare books and manuscripts.

Syria's war, which began with anti-regime protests, has spiralled into a multi-front conflict that has killed more than 240,000 people.

On Sunday, at least 31 people including eight children were killed in government air strikes on rebel-held Eastern Ghouta outside Damascus, the Observatory said.

Syria's Al-Watan newspaper, which is close to the government, said the regime was responding to heavy rocket fire from the area.