New raids, 'several' arrests over London attack: Police

British police today made several arrests in two dawn raids following the London attack claimed by the Islamic State group which left seven people dead.

"At around 4.15 today... officers from the Met's Counter-Terrorism Command investigating the London Bridge terror attack entered two further addresses -- one in Newham and another in Barking. A number of people have been detained and are at present being spoken to," a statement said.

In earlier raids in the ethnically diverse London suburb of Barking, police arrested seven women and five men aged between 19 and 60 at two properties in the hours after Saturday night's rampage.

A 55-year-old man was later released.

The attackers ran people over with a van on London Bridge, then lunged with knives seemingly at random at crowds gathered around Borough Market, which is full of restaurants and bars.

A vigil for the victims will take place at nearby Tower Bridge today.