Saudi Arabia has begun constructing a 600 mile wall along its northern border to keep out IS fighters.

SAUDI Arabia has begun constructing a 965km wall along its northern border with Iraq in an effort to keep out ISIL fanatics.

ISIL jihadists raided a post on the border near Judayyidat Ararm on January 5, killing three Saudi guards including a commander, in an apparent attack on the construction of the wall.

Four ISIL militants were also killed in the skirmish which included a suicide bombing.

The UK Telegraph reported that the wall was first proposed in 2006 but building work began in September last year.

The completed wall will consist of twin fences and a ditch, and will extend from near Turaif, where Saudi Arabia meets Iraq and Jordan, to Hafar al-Batin, on the Kingdom’s border with Iraq and Kuwait.

Saudi Arabia is known as the “home of Islam” and contains two of the religion’s most holy sites — the cities where the prophet Mohammed was born (Mecca) and died (Medina). The majority of Saudi Arabians are Sunni Muslims.

RELATED: Yemen Al-qaeda affiliate claims responsibility for Paris attacks

Experts have warned that the rise of ISIL in Iraq and Syria — and its proclamation of a global caliphate — will put it on a collision course with Saudi Arabia.

“ISIL regards the ultimate capture of Saudi Arabia, home to the ‘Two Holy Mosques’ of Mecca and Medina, as a key goal,” the Telegraph reported.

But it is not the only border of concern to Saudi Arabia at the moment.

Yemen may become a more important battleground in the competition between Saudi Arabia, which sees itself as a champion of Sunni interests, and Iran, which supports Shiite fighters. Both countries appear to be manoeuvring for influence.

Prince Saud al Faisal, the Saudi foreign minister, has been trying to round up allied support, warning late last month of “accelerating and extremely dangerous conditions” in Yemen.

The Saudis, who share a porous 850-mile (1367km) border with Yemen, fear Iran will seek to use Houthi rebels in Yemen as a destabilising force.

A US State Department official said the Iranian government has provided arms and possibly money to the Houthis in the past.

“The influence of Iran on the Houthis is absolutely there,” he said.

Iran denies any role in the conflict.