San Francisco, May 25 : The Covid-19 lockdowns in China are likely to hamper the development of at least one of Apple's upcoming flagship iPhones this year which has fallen behind schedule, the media reported on Wednesday. According to Nikkei Asia, the tech giant has "told suppliers to speed up product development efforts to make up for the lost time", which, in the worst-case scenario, could "impact the manufacturing schedule and initial production volumes of the new phones". Lockdowns in and around Shanghai began in late March as part of China's strict zero-Covid policy, and the impact on supply chains continues to linger despite an easing of restrictions. "It is challenging to make up for the lost time. Apple and its suppliers are working around the clock to speed up development," an executive with an Apple supplier was quoted as saying in the report. The ongoing Covid-19 lockdowns in China are set to make a huge dent in Apple revenue for the April-June quarter as the company has indicated up to $8 billion loss in sales especially owing to the Shanghai lockdown. The company is preparing four new iPhone models for this year -- iPhone 14, 14 Pro, 14 Max and 14 Pro Max. The iPhone 14 and Pro models will come with 6.1-inch screens, while the Max and Pro Max models will be equipped with 6.7 in-inch screens. However, the tech giant might discontinue the 5.4-inch iPhone mini this year. Currently, the four new phones are in the engineering verification test (EVT), stage of development, according to the report. Apple, Pegatron and Foxconn declined to comment on the report. Apple CEO Tim Cook had said in an earnings call last week that "we have estimated the constraints to be in the range of $4 to $8 billion and these constraints are primarily centred around the Shanghai corridor". "The Covid-related disruptions are also having some impact on customer demand in China," added Apple CFO Luca Maestri. /IANS