Anderson expressed concern after the Ecuadorean embassy in London had revoked Assange's visitor privileges and Internet access, saying she was anxious about his health and well-being, The New York Post's Page Six reported.More news: United States to impose sanctions on Russian Federation over attack on Skripals
There have also been reports that Ecuador and Britain have reached, or are about to reach, a deal on ending the asylum for Assange. The letter says the committee requests Assange make himself available for a closed-door interview "at a mutually agreeable time and location".
WikiLeaks said Wednesday that its founder Julian Assange was "considering" a request by a US Senate committee to testify about alleged Russian interference in the 2016 US elections.
"According to Moreno, Ecuadorian authorities are now in talks with Assange's lawyers to work out an agreement that would ensure the security of the WikiLeaks' founder "'in line with the norms of worldwide law".More news: Jurgen Klopp hopes Liverpool can challenge in the Premier League
He was granted asylum in 2012 to avoid extradition to Sweden, where he was accused of sex crimes, allegations that were later dropped.
Ahead of the 2016 election, WikiLeaks published emails hacked from the Democratic Party and the personal email account of John Podesta, Hillary Clinton's campaign chairman.
He fears that if he leaves the building he will be extradited to the USA for questioning over the activities of WikiLeaks, which has published reams of military and diplomatic secrets.More news: Pochettino reacts to latest Bale to Spurs transfer rumours
On a visit to Madrid last month, Ecuadorean President Lenin Moreno confirmed that Ecuador and Britain were in talks to try to end his stay at the embassy. In July, special counsel Robert Mueller indicted 12 Russian military intelligence officers allegedly behind the "fictitious persona" Guccifer 2.o.