United Nations: The spillover in the Golan Heights from the conflict in Syria has intensified in recent days, posing a threat to UN peacekeepers on the scene, a senior UN official said on Tuesday.

The Syrian army and opposition rebels have engaged in “intense shelling and heavy clashes” since August 17 in a UN-patrolled zone that separates Israel and Syria, Oscar Fernandez-Taranco, assistant secretary-general for political affairs, said.

No casualties have been reported so far, but the fighting has intensified near two UN positions, forcing peacekeepers to take shelter, he said.

The UN Disengagement Observer Force (UNDOF) “observed the continued presence of road blocks with improvised explosive devices in the vicinity of UN positions which affects the freedom of movement of UNDOF personnel,” he said.

“Incidents of threatening behaviour against UNDOF personnel from armed members of the opposition were also reported,” he said.

Meanwhile, Israeli forces returned fire on Saturday after Syrian shells fell on a part of the Golan occupied by Israeli troops.

Israel’s ambassador to the United Nations, Ron Prosor, protested against the shelling in a letter to the UN Security Council, warning “these sorts of provocations will not be tolerated.”

UNDOF has been monitoring the ceasefire between Israel and Syria since 1974.

The situation in the Golan has been tense since the start of the conflict in Syria more than two years ago.

Israel, which is technically at war with Syria, captured 1,200 square kilometres of the Golan Heights during the Six Day War in 1967, and then annexed it, an action never recognised by the international community.