The preservation of monuments in Syria and Mali pose some of the biggest challenges on a list of 67 global sites that need protection, a foundation warned Tuesday.

Unveiling its watch list for 2014, the World Monuments Fund (WMF) warned that conflict, catastrophe, lack of resources, development pressures and loss of cultural traditions threaten sites in 41 countries.

For the first time, all heritage sites in Syria and Mali have been included on the list, which is normally dedicated to individual sites.

Mali and Syria have some of the oldest sites on the list, with the cliff of Bandiagara known to have been inhabited tens of thousands of years ago.

The citadel in Aleppo, the northern Syrian city torn apart by a 30-month civil war war, dates back to the early Bronze Age, 3300-2200 BC.

"In Syria, the ongoing civil conflict has a terrible toll on monuments and sites which continues. We placed the entire country of Syria in the watch list," said WMF president Bonnie Burnham.

"In the spirit of solidarity we also placed the cultural heritage of Mali on the watch list... A lot of damage has been done," she added.

The United Nations says more than 100,000 people have been killed in the conflict in Syria.

Islamist insurgents are also fighting in Mali, where France launched a military operation in January against Al-Qaeda-linked groups occupying the north.

Burnham said WMF would do "everything we can" to help those sites on the list, compiled every other year, over the next 48 months.

WMF says it seeks to raise awareness of the threats, and to galvanise the skills and resources of the global community for a time when it is safe to return.

WMF also singled out Venice, long a source of concern due to flooding, because of a rising number of large cruise ships visiting the Italian city.

"Experts believe that is pushing Venice to an environmental tipping point and undermining the quality of life of its citizens," Burnham told reporters.

Cruise-ship tourism to Venice has increased by 400 percent in the last five years with around 20,000 visitors a day during peak season, WMF said.

In Yangon, Myanmar it also warned that a sudden rush to build more commercial and residential property is threatening to destroy the aura of the city center and result in the demolition of its historic landmarks.

Since it was set up in 1996, WMF has included mroe than 740 sites on its watch lists, which has resulted in $300 million being invested in their preservation.

There are four sites on the list in England, including Battersea Power Station in London which closed in 1983, and six in the United States, including the Jefferson National Expansion Memorial in St Louis, Missouri.