The so-called “White Widow,” a British-born Muslim accused of terrorism, was reportedly killed by a Russian sniper in eastern Ukraine, a Russian news agency reported Wednesday. Samantha Lewthwaite is known as the “White Widow” because she is the widow of a suicide bomber who killed dozens in a terrorist attack on London’s transportation system in July 2005.

The Regnum news agency alleged that Lewthwaite was shot and killed two weeks ago while fighting with Ukrainian forces against pro-Russian rebels seeking to advance westward, according to the New York Post . The claim has not been officially confirmed and the Russian news service did not name its source. British officials said they have no evidence of Lewthwaite in Ukraine, according to British news reports from outlets such as the Telegraph and the Mirror.

Several recent reports had claimed the 30-year-old Muslim convert was training ISIS female jihadists to become suicide bombers in Syria. Authorities have long-sought Lewthwaite for her possible connection to the Westgate Shopping Mall terrorist attack in Kenya last year that left 67 people dead, according to several news sources including CNN and ABC News.  In 2011, Lewthwaite was charged with possessing explosives and conspiracy to commit a felony when officials found bomb-making supplies in her Kenyan home. The materials were similar to the ones used on London buses in the 2005 terrorist attack.