Al Gore yesterday urged Beijing students to 'challenge existing institutions', predicting the mainland's market reforms must inevitably lead to political freedom. Mr Gore, speaking to hundreds of students at Qinghua University, appealed to young Chinese to consider 'this is a moment when, to a unique degree, great things do hang in the balance'. 'Old ways of doing things, old ways of thinking and institutions built upon these old ways are being swept aside by great, powerful waves of change,' he said in a carefully worded address. He is the most senior United States official to visit China since the 1989 Tiananmen Square crackdown. Mr Gore made no direct reference to the crackdown, but said: 'We believe in a world in which nations conduct their affairs, both outside their borders and within, according to the rule of law tempered by a love of justice. 'Americans believe the freedom to inquire and debate and, when necessary, to challenge existing institutions and habits of thought is the key to creating the world I just described.' His speech drew polite applause from the students. 'We also believe economic freedom and political freedom ultimately are linked,' he added. 'They must ultimately rely on one another.' Mr Gore's speech, his only public address on a four-day state visit to the mainland, came nearly eight years to the day after students from Beijing University first marched on Tiananmen Square chanting 'long live democracy' in a memorial protest for Communist Party reformer Hu Yaobang . 'We value individuality more than consensus,' Mr Gore declared. 'We value history, as you do, but rather as a way to learn how we can do better.' Authorities did not comment on the Vice-President's speech.