SHANGHAI — Censors have blocked the latest film by Lu Chuan, one of China’s rising helmers, as local filmmakers expressed their frustration saying censorship puts them at a disadvantage in competing with Hollywood.Lu was hoping to bow “The Last Supper,” a costume drama about two warring generals starring Liu Ye, Daniel Wu and Taiwanese thesp Chang Chen, next month. However, an emotional Lu told a forum at the Shanghai Film Festival the project had been delayed by the Film Bureau. “We need a fair, relaxed and comfortable environment to be creative, like Hollywood. Their movies can have aliens attacking Los Angeles, even flooding the White House. Film should not just be a propaganda tool,” he told the forum. In attendance was a group of China’s top young helmers including Jia Zhangke, Wang Xiaoshuai, Zhang Yuan, Wu Ersan, Guan Hu, and Lou Ye, and all complained about how censorship was making it difficult to make movies. Han Sanping, head of the state-run China Film Group, was supposed to attend the event but didn’t show up. Lu’s “City of Life and Death” won best picture at San Sebastian and grossed more than $24 million in China in 2009. Its account of the 1937 attack on the city of Nanjing by Japanese military wound up as a yardstick by which censors judge permissibility, one that “The Last Supper” seems to have failed. If the pic’s release is delayed until August, it will go head-to-head with Hollywood tentpoles including “The Amazing Spiderman,” “The Bourne Legacy” and “The Expendables 2.” Lu is well-known as the most uncompromising of the so-called Sixth Generation of filmmakers who believes that filmmaking is art, not business. But he understands how funding works. “This year is a crisis year for Chinese films. If we lose today, it’s possible more funding will go to Hollywood, not China,” he said, referring to the increased quota for foreigh films. “And what happens next year?” Producer Qin Hong said he hoped the forum would encourage the Film Bureau to change its mind.