Israeli Prime Minister Benjamin Netanyahu accused Iran of turning Syria into a "base of military entrenchment as part of its declared goal to eradicate Israel", according to BBC.

Netanyahu's comments were made during talks with UN Secretary General António Guterres in Jerusalem, marking Guterres's first visit to the region since taking office in January.

Iran's forces are supporting President Bashar al-Assad in the Syrian Civil War, and back Lebanese Hezbollah. 

Netanyahu gave no details about the sites Iran was allegedly building to manufacture missiles, but he warned "this is something Israel cannot accept".

Two weeks ago, ImageSat International, an Israeli satellite imagery company, published photographs it said appeared to confirm a report that a missile factory was under construction in north-west Syria under Iranian oversight. The report was issued by a Syrian pro-opposition newspaper.

The facility is allegedly being constructed in Wadi Jahannam, near the coastal town of Baniyas, and closely resembles a missile factory near Tehran, according to ImageSat International. 

There was no comment from Iran, which takes a highly critical stance against the apartheid state.

Netanyahu also pressured Guterres on the UN peacekeeping force in Lebanon, stating that it failed to keep Hezbollah from building its armed force since the Israel-Hezbollah war in 2006.

"I understand the security concerns of Israel and I repeat that the idea or the intention or the will to destroy the state of Israel is something totally unacceptable from my perspective," he added.

Guterres is set to meet Palestinian Authority Prime Minister Rami Hamdallah in Palestine, and will travel to the Gaza Strip shortly afterwards.