A Syrian official on Thursday called on the international community to protect the 2,000-year-old ruins of the ancient city of Palmyra, now threatened by advancing Islamic State militants.

Maamoun Abdulkarim, Syria's director-general of antiquities and museums, told The Associated Press by telephone that the U.S.-led coalition, which has been striking the extremists in Syria since September, should expand its raids to hit IS fighters battling government forces at the gates of Palmyra.

"If Daesh enter the city it will be a human catastrophe," he said, using an Arabic acronym for the group. "If Daesh enters the city it will mean destroying the temples, ruins and tombs."

Palmyra is known for its Roman-era ruins, which once attracted thousands of tourists, who came to see its towering colonnades and a temple to the god Baal.

The UNESCO world heritage site in the ancient oasis city is Syria's most famous, and includes other attractions such as a theater, Efqa Spring and the Temple of Baalshamin.

Since Syria's conflict began in March 2011, looters have stolen artifacts from museums and damaged the ruins of Palmyra.

The Islamic State group has destroyed archaeological sites in neighboring Iraq in recent months. The Sunni extremists, who have imposed a violent interpretation of Shariah law in the territories they control in Syria and Iraq, believe ancient relics promote idolatry.

The militants have released videos in recent months showing fighters proudly destroying artifacts with hammers and drills in a museum in the northern Iraqi city of Mosul and using explosives to wreck other sites.

In March, IS members in Iraq razed 3,000-year old Nimrod and bulldozed 2,000-year old Hatra -- both UNESCO world heritage sites. The move was described by U.N. Secretary General Ban Ki Moon as a "war crime."

"We hope that the experience that Iraq passed through is not repeated," Abdulkarim said. "We need international solidarity to stop these thoughtless methods of the criminal Islamic State group."

"This is not Syrian heritage only. It is international," he said.

But it was unclear whether the U.S.-led coalition would launch airstrikes that would effectively aid Syrian government forces defending the site. The U.S. supports rebels fighting to topple Syrian President Bashar Assad and insists it is not coordinating strikes with his government.

The Britain-based Syrian Observatory for Human Rights said IS fighters entered several buildings east of Palmyra before they were pushed back by government forces. Syrian state TV said troops repelled infiltration attempts east of the city, killing some IS fighters.

The Observatory said IS members "executed" 26 people, including 10 who were beheaded, near the city of Palmyra after accusing them of being government agents.

The city is also home to a notorious prison that carries its name in Arabic, Tadmur, where many members of the outlawed Muslim Brotherhood as well as other detainees have been held for years.

In 1980, followers of the brother of then-President Hafez Assad reportedly killed hundreds of prisoners in the Tadmur prison. Rifaat Assad's Defense Companies were said to be behind the killing of 500 to 1,000 prisoners in a single day after Assad, the current president's father, escaped an assassination attempt.

Earlier Thursday, a prominent Iranian lawmaker called a U.S.-backed plan to train moderate Syrian rebels to battle IS a "strategic mistake" that will fuel terrorism.

Alaeddin Boroujerdi, who heads the Iranian parliament's national security and foreign policy committees, made the remarks during a high-profile visit to Damascus. The Syrian government has said the program will complicate efforts to reach a political solution to the conflict, now in its fifth year.

The training started in Jordan earlier this month with about 90 rebels and is due to be expanded to include training in Saudi Arabia, Qatar and Turkey. U.S. officials say the program is part of a broader effort to combat the IS group - not Assad's forces. Many rebels have criticized that narrow focus and said the assistance is too little, too late.

"This is a strategic mistake by the U.S. and allies in the West," Boroujerdi said. "It only reveals the real hated and despicable face of what they do in terms of training and preparing terrorists." He went on to reaffirm Iran's support for Assad's "stable and permanent" government.

The Syrian government also describes the rebels fighting to topple Assad as "terrorists."

Boroujerdi's visit comes as Syrian forces have suffered a number of battlefield setbacks.