Jerusalem (Web Desk): The Israeli army on Thursday revealed details of a massive underground barrier being built along the border with the Gaza Strip , foreign media reported.

Eventually stretching some 65 kilometres (41 miles), the concrete wall will be accompanied by motion sensors designed to detect tunnel digging and is expected to be completed by mid-2019.

The project had been previously announced, but details of its construction had been kept secret until Thursday, when journalists were allowed to view aspects of it.

Workers -- local and from abroad -- have been labouring around the clock for nearly a year.

The barrier is being built on Israeli territory, east of the existing border fence, with four kilometres completed so far -- in the area of the town of Sderot, off the northern Gaza Strip , and the Nahal Oz area near Gaza City.

The technique used is similar to that for building support walls for high-rise buildings or underground parking lots.

Tunnels were among Hamas 's most effective tools during the 2014 war with Israel , which claimed lives of about 2,251 Palestinians, while injuring more than 10,000 and 100,000 were left homeless.

On the Israeli side, only 74 people were killed, all but six of them soldiers.