Concerns as Islamic State militants near UN world heritage site of Palmyra

Concerns have been raised as fighting between Islamic State militants and the Syrian army was reported on Saturday near an ancient citadel in the historic city and UN world heritage site of Palmyra.

The Syrian Observatory for Human Rights, a UK-based group that reports on the war, also said Islamic State militants had executed 23 people on Friday including nine minors and five women in areas seized from state control outside the city.

It marks the second mass execution reported since Islamic State advanced this week into the area some 240 km (150 miles) northeast of Damascus. In the first, the Observatory said the jihadists had executed 26 men, beheading 10 of them.

It reflects the pattern of attacks by the group elsewhere.

The Islamic State offensive in central Syria has added to the pressures facing government forces that have faced significant setbacks since late March in the four-year-long war.

Palmyra, also known as Tadmur, is home to extensive ruins of one of the most important cultural centres of the ancient world and was put on UNESCO's list of World Heritage in danger in2013.