South African President Jacob Zuma said on Thursday that the condition of ailing anti-apartheid hero Nelson Mandela had improved overnight and was now critical but stable. "He is much better today than he was when I saw him last night. The medical team continues to do a sterling job," Zuma said in a statement. After visiting Mandela for a second time in 24 hours, Zuma urged South Africans to pray for the 94-year-old former president. Zuma "was informed by the medical team that Madiba's condition has improved during the course of the night. He remains critical but is now stable," the presidency said. "We must pray for Tata's (father's) health and wish him well. We must also continue with our work and daily activities while Madiba remains hospitalised," Zuma said. The presidency also urged people to refrain from spreading rumours about the man many South Africans regard as the father of their nation, amid numerous false reports of his death.