KABUL: An important archaeological site in northern Afghanistan that was occupied by humans as far back as the sixth century BC is being threatened by the construction of a road, archaeologists warn.

The picturesque Cheshma-e-Shafa gorge in the northern province of Balkh is just one of several ancient sites faced with destruction by a post-Taliban push for development, they say.

This is despite laws in place to protect the country's heritage.

Traces of ancient human habitation were discovered in 2007 at Cheshma-e-Shafa, about 30 kilometres (20 miles) southwest of the city of Mazar-i-Sharif, says the French Archaeological Delegation in Afghanistan (DAFA).

They were found to date back to the Achaemenid period (sixth to fourth century BC), named after the first Persian dynasty that reigned over the area until its removal by Alexander the Great.

But a South Korean company has been contracted by the government to build a road through the site, said DAFA director Roland Besenval, heading excavations.

"We had stopped the bulldozers by putting ourselves in front of them but they restarted the work the next day," he told AFP.

"They could divert the road towards the east but clearly they don't want to.

"Afghan laws prohibit the destruction of archaeological sites. The ministry of public works knows about all of this, the ministry of culture too," he said.

According to DAFA, engineers from the Korean Samwhan Corporation had said in a meeting they would have to use dynamite to blow up the narrow gorge to let the road through.

Citing an email, DAFA said that despite their pleas, the company intended to push ahead with the project.

"The government authorities have ordered us to proceed with the road construction as per our approved road construction drawings regardless of the concern you mentioned in the meeting," the email said.

The area was occupied until the 13th century and was on the route used by Alexander the Great and other conquerors, DAFA said.

"It is a site which controlled an old route by which people could come from Central Asia to India, a place completely strategic for controlling traffic," DAFA scientist Philippe Marquis added.

"Then the Mongols passed through around 1220 and destroyed the whole region and the area then lost strategic interest," he said.

Among its features are walls standing 15 metres (50 feet) tall and nine metres thick and a Zoroastrian fire temple that is "one of the most ancient in the world", according to DAFA.

Zoroastrianism is one of the world's oldest religions and was founded by Zarathustra, who is believed to have lived in the ancient city of Bactria, now called Balkh and about 30 kilometres north of Cheshma-e-Shafa.

"Zarathustra would have stayed here," said Marquis, referring to the threatened site.

Afghanistan's rich ancient heritage has been plundered, neglected or destroyed during decades of war.

One of the best-known examples is the 2001 destruction by the Islamist Taliban regime of the famed statues of Bamiyan Buddhas.

Other important excavations also threatened by construction are in the western province of Herat and in Logar, near Kabul, where an ancient city dating back 1,700 years is threatened by a planned Chinese-funded copper mine.

"There is a new type of problem for Afghan heritage -- that is the confrontation with development," Besenval said.