Police in London have issued a warning after a rise in thefts at knifepoint of luxury watches in some of the city's most affluent areas. They said criminals on mopeds or e-bikes have attacked victims wearing expensive watches. Recent attacks in July include a couple who were followed in Chelsea at 10.10am by a moped rider who threatened them with a machete before they were forced to hand over their Audemars Piguet and Patek Philippe watches; two people on a motorbike approached a woman in Chelsea and threatened her with a knife, forcing her to hand over her watch and bracelet; two people on a motorbike knocked down a man in his 50s, then produced a knife and took his £20,000 Rolex watch and his wedding ring. Detectives investigating the high-value watch robberies are appealing for the public’s help to identify those responsible. Over recent weeks the number of knifepoint robberies where victims have been ordered to hand over their watches has increased. In the Metropolitan Police's central zone, which includes Westminster, Kensington and Chelsea and Hammersmith and Fulham, 67 offences were recorded last month, an increase of 60 per cent on the 42 watch robberies in May. Police said a targeted operation has now been launched by officers in the area to tackle these robberies head-on and prevent them from taking place. In a statement, the police said that during the summer, bigger crowds of people and more densely packed streets create a more agile operating ground for street robbers. Det Chief Supt Owain Richards said: “We want people living in and visiting our city to enjoy the summer safely — no one should have to go about their day in fear of thieves. “Sadly across Westminster and neighbouring boroughs we are seeing a rise in these offences as criminals take advantage of the longer days and the busy streets. “Extra officers have been put in place in locations where these crimes are most common. “This is a top priority for us.” Last year, the <a href="https://www.thenationalnews.com/world/uk-news/2021/09/23/killer-of-omani-student-in-london-jailed-for-life-as-brother-condemns-cowardly-attack/" target="_blank">murderer of a wealthy Omani student near London department store Harrods</a>, who police believe had gone out with a plan to rob a suitable victim, was sentenced to jail for life. Badir Al Nazi fatally stabbed Mohammed Al Araimi, 20, the son of Omani developer Sheikh Abdullah Al Araimi, during an attack in 2019 that lasted only eight seconds. Police believe Al Nazi set his sights on Al Araimi, a student at King’s College London, because he was wearing a £37,000 Patek Philippe watch.