Images of prototypes for Donald Trump's proposed wall on the Mexican border have emerged.
New photographs show eight border wall prototypes being built in San Diego.
The prototypes are between five-and-a-half and nine metres high with four of them made from concrete.
The US Department of Homeland Security will start carrying out tests next week to determine which one will be ideal for hampering illegal immigrants trying to cross the border, Fox News reported.
Questions authorities will seek to answer will include what length of time would it take for a person to climb the wall or break through it, and whether the prototype has sensors to raise the alarm to border protection officers?
Six companies won the right to construct eight prototypes commissioned by the US Customs and Border Security.
Work began on September 26 and they were given 30 days to complete it, meaning the deadline is October 26.
The prototypes, which costs up to about $637,550 each, are designed to withstand an hour of assault from a sledgehammer, pickaxe, torch, chisel and battery-operated tools, according to Associated Press.
US Border Patrol spokesman Theron Francisco told AP: "The sheer size of them would be a challenge to get up and over, especially in any type of time, or fast period of time.
"Some of these that we can see through would give us the ability to see what's happening on the south side."
At the time of when construction started, US Customs and Border Protection acting deputy commissioner Ronald Vitiello said: "We are committed to securing our border and that includes constructing border walls.
"Our multi-pronged strategy to ensure the safety and security of the American people includes barriers, infrastructure, technology and people
"Moving forward with the prototypes enables us to continue to incorporate all the tools necessary to secure our border."
This comes as a second judge ordered a freeze on US President Donald Trump's newest travel ban order on Wednesday, saying it was essentially targeted at Muslims in violation of the US Constitution.
Maryland federal judge Theodore Chuang said the ban affecting travelers from six majority-Muslim countries and North Korea, as well as many officials from Venezuela, essentially had not changed from the first two versions, which were shot down in lower courts as discriminating against a single religion.
He pointed out, as in earlier rulings, Mr Trump had repeatedly promised a ban on Muslims coming into the country during last year's presidential election.
Judge Chuang was the second judge this week to order a block on the open-ended ban, issued in a White House executive order in September and which was to come in effect on Wednesday.
- with AFP
