London: Britain's most wanted female terrorist, Samantha Lewthwaite, commonly known as the "White Widow" is believed to have killed 400 people and has directed terror raids, suicide attacks and car bombings in Somalia and Kenya, a media report said on Monday.

According to official security reports, Lewthwaite, 32, and a mother of four, has murdered 400 people after becoming a key figure in Somalia-based terror group Al Shabaab. She is believed to be responsible for last month's attack at a university in Kenya in which 148 people were killed, Mirror online reported.