The United Nation's cultural watchdog on Tuesday condemned the destruction of the famed Temple of Bel in Syria's Palmyra by Islamic State jihadists as an "intolerable crime against civilisation".

UNESCO chief Irina Bokova expressed her "deep dismay" over the destruction of the temple but said the move would "not erase 4,500 years of history".

"The power of culture is greater than that of all forms of extremism and nothing can stop it," she said in a statement.

The 2,000-year-old temple was the centrepiece of Palmyra's famed ruins and one of the most important relics at the UNESCO-listed heritage site.

UNESCO said that satellite imagery showed the temple was destroyed on August 30 with explosives.

"In the face of this most recent war crime, UNESCO reaffirms its determination to go on protecting all that which can be saved," Bokova said in a statement.

"It will pursue its unrelenting fight against illicit trafficking in cultural objects, the documentation of sites, and the setting up of networks that link thousands of experts in Syria and all over the world, to transmit this heritage to future generations, notably with the help of modern technology.

UNESCO described the Temple of Bel as one of the best preserved in Palymra and one of the most important religious edifices of the first century in the Orient.

"Whoever saw Palmyra remains forever marked by the memory of the city which embodies the dignity of the entire Syrian people and humanity's loftiest aspirations," Bokova said.