In one of the attacks, he knocked a 23-year-old woman to the ground and touched her genitals before getting away on an electric bike along Central Park West, a block from the Museum of Natural History.
Police say the same man approached a 28-year-old woman from behind near Tompkins Square Park in the East Village.
The man claimed to have a knife and forced the woman to perform a sex act on him.
Both women sustained abrasions in the attacks.
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Ex-Brit turned Manhattan resident since 2008.