The craze sees gamers walk around the streets with their phones out while hunting for virtual creatures to collect.
The Met Police has urged players to be vigilant after an officer dealt with two phone thefts relating to the game in just one day.
Westminster MPS tweeted on Friday: “Sgt Blair has supervised his second #PokemonGO related phone theft of the day. Be aware of your surroundings.”
A teenager in Manchester was also arrested after three students were robbed of their phones as they played the game on July 15.
The Association of British Insurers has also warned users’ safety could be at risk when playing the game.
Ross Penstone-Smith, Policy Adviser for General Insurance at the ABI, said: “Playing Pokemon Go shouldn’t mean letting go of your senses.
“It’s important to remember that mobile phone users should always have their wits about them, drive carefully and watch out for hazards.
“While insurers will be there to help customers when they have accident or are victims of crime, it’s best for everyone if risks are avoided in the first place.
“Following these simple principles should reduce those risks while still allowing gamers to play to their hearts’ content.”