Jerusalem (AFP) - Israeli Prime Minister Benjamin Netanyahu took to Twitter on Saturday to hail new US President Donald Trump's decision to build a wall on the border with Mexico.

On Wednesday, Trump signed an executive order telling officials to begin to "plan, design and construct a physical wall" along the 3,200-kilometre (2,000-mile) US-Mexico border, making good on a campaign pledge.

In an interview with American channel Fox News on Thursday Trump justified his decision, citing Israel which, he said, had managed to "stop 99.9 percent" of illegal immigration by constructing a wall.

He was referring to the more than 240-kilometre barrier Israel completed in 2014 along its border with Egypt, a route previously taken by many African illegal immigrants and traffickers.

"President Trump is right. I built a wall along Israel's southern border. It stopped all illegal immigration. Great success. Great idea," Netanyahu tweeted in English, adding the Israeli and American flags.

Several hours later, foreign ministry spokesman Emmanuel Nahshon said in a tweet, also in English, that Netanyahu "referred to our specific security experience which we are willing to share. We do not express a position on US-Mexico relations."

Netanyahu, who heads one of the most right-wing governments in the history of the Jewish state, has not hidden his admiration for the new US president.

The Israeli premier's most nationalist allies see in Trump's administration the chance to continue building Jewish settlements in occupied east Jerusalem and the occupied West Bank.

Israel announced a major settlement expansion in the days after Trump's January 20 inauguration.

On Sunday, the city planning committee approved building permits for 566 settler homes in east Jerusalem.

Two days later, the defence ministry announced plans for 2,500 settler homes in the occupied West Bank.

And on Thursday, Israeli officials gave final approval to 153 east Jerusalem settler homes.

The announcements have deeply concerned those seeking to salvage a two-state solution to the Israeli-Palestinian conflict.