Former president Hu Jintao made a rare public appearance at a university in Hunan province yesterday. Hu arrived at Hunan University at about 10am and visited several historic institutions on the campus, including the Yuelu Academy, founded in AD976 and one of the four most prestigious academies in ancient China, the university's television station reported on Sina Weibo. Hu's appearance was an indirect way to voice support for the current state leaders, and to offer some comfort to former allies, some of whom were said to be targets of Xi's campaign, said Gu Su, a professor of political science at Nanjing University. News outlets, including state media, were quick to report the visit. Depite keeping a low profile in retirement, Hu's appearance - at the height of his successor Xi Jinping's anti-corruption campaign - sends a message that he still wields influence, observers said. Hu's only other official public appearance since he retired was at his ancestral home in Anhui late last year. Photos posted in the same report showed Hu dressed in a casual black jacket and wearing white sneakers, which many microbloggers noted was a departure from his "formal and boring" image as a state leader. Former leaders must seek their successors' approval before making any high-profile appearances, Gu said. Hu's visit took place at a politically sensitive moment, said Zhang Lifan, a Beijing-based political affairs commentator. "The party is very unstable. The probe against the 'big tiger' [a euphemism for former security tsar Zhou Yongkang ] has yet to be announced, while the target group of Xi's anti-graft campaign has been widened to include the military and reportedly the Communist Youth League faction [Hu's former power base," Zhang said.