A frail man was left sprawled on the ground after being violently robbed by two teenagers.

The 64-year-old, who suffers from osteoporosis causing his bones to be weak and fragile, was stuck on the ground for about an hour after the unprovoked attack.

He was knocked down by two youths who accosted him while he was walking up Christchurch Hill, Hampstead, at about 10.30pm on Monday.

The youths, aged about 16 or 17, had walked towards him and said “all right mate”, before punching him in the side of his face when he looked round.

As he lay on the floor, they pulled three gold rings off his fingers and grabbed his wallet.

Police believe the teenage boys had been “scoping” out the area and The Wells Tavern in nearby Well Walk.

Both suspects were in grey jogging bottoms, red and grey coats and white trainers.