Belmarsh has frequently been used in high-profile national security cases, including that of former Finsbury Park Mosque hate preacher Abu Hamza, who now resides in a USA "supermax" prison following extradition.
Moreno also reiterated the claim made by the Ecuadorean government that Assange's hygiene and behavior constituted an "aggressive campaign against Ecuador" from inside the embassy.
"Ecuador has made these allegations to justify the unlawful and extraordinary act of letting police come inside an embassy", Robinson told the UK's Sky News.
In a video announcement after Assange's arrest, Moreno accused Assange of "discourteous and aggressive behaviour" inside the embassy, and said that WikiLeaks made "hostile and threatening declarations" during Assange's time in the embassy.
President Moreno of Ecuador said in an interview that Assange had "bothered and threatened guards; [and] hit and mistreated employees of the embassy".
A lawyer for the Australian hacker, who remains jailed in London pending a ruling on possible extradition to the USA, has accused Ecuador of hurling "outrageous allegations" to distract from their "unlawful" abandonment of her client.
Assange was arrested last Thursday.
"It is unfortunate that, from our territory and with the permission of authorities of the previous government, facilities have been provided within the Ecuadorian embassy in London to interfere in processes of other states", Lenin Moreno told The Guardian newspaper on Sunday.
While Assange awaits the very likely possibility of extradition to the USA and prosecution for reporting on the sins of the world's most powerful, mainstream media "journalists" are doing humanity another great service - by posting irrelevant videos and pictures taken inside the embassy in an effort to assist Quito in its smearing efforts.
An image tweeted by WikiLeaks on May 9, 2016, shows founder Julian Assange holding a kitten given to him by his children to keep him company where he remains holed up in the Ecuadorean Embassy in London.
After his arrest last week, Assange was taken to Westminster Magistrates' Court in London, where he was found guilty of breaching his bail conditions, and U.S. officials charged him with conspiracy.
U.K. Home Secretary Sajid Javid would be expected to have the final say in which extradition claim takes priority, if Sweden does file a new one.
If Stockholm makes a formal extradition request, the British government will have to decide whether to consider it before or after that of the United States.
He has not formally responded to the US conspiracy charge.