The Hamas-run government in Gaza bulldozed part of a UNESCO heritage site to expand a military training zone.

The military wing of Hamas, the Izz ad-Din al-Qassam Brigades, bulldozed a part of the ancient Anthedon Harbor in northern Gaza along the Mediterranean Sea last month, the Al-Monitor news website reported.

The 3,000-year-old seaport discovered in 1997 was named an international heritage site by UNESCO in 2012, and is the oldest harbor in Gaza. It contains mosaic floors with historical pillars from the Roman, Byzantine and Islamic ages, according to Al-Monitor.

Much of the port is covered with sand to protect the artifacts until they can be excavated.

The monitoring organization UN Watch sent a letter on Monday to UNESCO Director-General Irina Bokova calling for immediate action to stop the bulldozing of the port “for use as a terrorist training camp.” A copy also was sent to European Union foreign policy chief Catherine Ashton calling on the EU to take action.