Experts have complained that the roughly three-mile stretch of steel posts was built too close to the Rio Grande that separates the US and Mexico, and that erosion of the organic material helping stabilise the fence’s foundation has begun to erode, ProPublica and the Texas Tribune have reported.

Mr Trump tweeted his dissatisfaction with the private portion of the wall on Sunday.

“I disagreed with doing this very small (tiny) section of wall, in a tricky area, by a private group which raised money by ads,” the president wrote. “It was only done to make me look bad, and perhaps it now doesn’t even work. Should have been built like rest of Wall, 500 plus miles.”

Mr Trump was responding to the report from ProPublica and the Texas Tribune.

The CEO of Fisher Industries, Tommy Fisher, dismissed such concerns, telling the AP he believed Mr Trump “just got some misinformation on this stuff” while reaffirming his “complete respect” for the president.

“The wall will stand for 150 years, you mark my words,” Mr Fisher told the AP.

Mr Trump, meanwhile, has continued to tout the border wall’s development, tweeting that the US has built 240 miles of it under his watch and promising hundreds more miles by the end of the year.