Assange has been facing extradition to the United States and rape charges.
Assange's partner, in court documents and a video posted on Saturday by WikiLeaks and the Daily Mail, said that the couple conceived two-year-old Gabriel and one-year-old Max as Assange was wanted in the United States for leaking classified intelligence materials and in Sweden for rape allegations, an attorney for Assange confirmed the news to Washington Post on Sunday.
Moris, according to the attorney, said that she revealed the relationship because she wanted 48-year-old Assange to be released from London prison, where he landed after the Ecuadorian Embassy rescinded his political asylum a year ago, amid the coronavirus outbreak which is spreading among the UK's prison population.
In the documents, Moris further said that Assange's health is already precarious because of a lung condition as well as mental health challenges after extended isolation.
"I make this statement now only because our lives are on the brink and I fear that Julian could die," Moris said in the statement filed with the court in support of an application Assange's attorneys submitted, to have him released on bail.
She added, "He may himself die as a result of increased risk of exposure to the COVID-19 virus."
Westminster Magistrates Court judge Vanessa Baraitser refused his bail request on March 25. Since then, one prisoner in the high-security Belmarsh prison, where Assange is lodged, has died after contracting the virus, according to local media reports.
It is, however, unclear if Assange's legal team will make a second bail request.
Moris said in the video that she fell in love with Assange after meeting him in 2011 and joining his international legal team, which led her to spend "almost every single day" in the embassy.
In the video, she flips through photos of the children, a cat beside her, remarking at one point that the older boy resembles Assange: "Very Julian."
The children, both British citizens, have visited their father in Belmarsh, according to British media. It also reported that Assange watched his children's births over video and that he was able to secretly meet Gabriel in the embassy.
Meanwhile, the Ecuadorian foreign ministry and US officials have declined to comment on the matter.
Assange is challenging an extradition request by the United States, which wants the 48-year-old Australian to stand trial in federal court in Northern Virginia on charges that he violated the Espionage Act.
Prosecutors allege that Assange helped obtain and disseminate hundreds of thousands of pages of secret military documents and diplomatic cables regarding US action in the wars in Iraq and Afghstan.
According to prosecutors, Assange has also helped Chelsea Manning, a former Army intelligence analyst, hack into government computers.
( With inputs from ANI )