"Julian Assange and Stella Moris will marry in HMP Belmarsh surrounded by only a handful of friends and family on Wednesday. Their engagement was announced in November 2021 and over months of back and forth with the governor and prison authorities, the couple have been granted permission to marry inside the prison," the statement, issued Tuesday, read.
"Only four guests and two witnesses will be allowed to attend the ceremony, as well as two security guards. The guests will have to leave immediately after the event, even though it is being held during normal visiting hours," it added.
The statement also said top British fashion designer Vivienne Westwood is designing Moris' wedding dress and a kilt for Assange.
Assange's parents are of Scottish descent, according to Wikileaks.
"Stella Moris is expected to cut a wedding cake and give a speech after their wedding ceremony has concluded," the statement added.
Hundreds of Assange supporters have planned to gather outside the prison for this event, according to WikiLeaks.
Assange and Moris have two children together.
Assange has been charged in the United States under the Espionage Act for his role in publishing classified military and diplomatic cables and is currently in jail at the high-security London prison.
On March 15, the UK Supreme Court refused to allow Assange his latest appeal against extradition to the US. The court said his application did not raise "an arguable point of law," constituting a major blow to Assange's hopes of avoiding extradition.