After a referral from Rwanda, British detectives are investigating five people living in the UK over allegations relating to the genocide in 1994.
The Daily Mirror reported that a man from Essex and a man from Bedford are among the suspects.
Around 800,000 Rwandans, mostly Tutsis, but also some moderate Hutus, died in 100 days of ethnic cleansing in 1994.
A Met Police spokeswoman confirmed the force's war crimes unit received a referral from Rwandan authorities in January last year.
All five suspects deny the allegations against them and any involvement in the genocide.
In July 2017, five men with the same names and of Hutu ethnicity had an extradition bid to have them returned to Rwanda blocked by the UK High Court. Judges agreed there was a real risk the men would be denied a fair trial if they went back.