Thousands of police have been standing guard in Islamabad as Pakistan hosts its leg of the Olympic torch relay.

Protests against host-country China's human rights record have marred the torch's passage through Western cities and Pakistan has gone to great lengths to avoid any repeat during the Olympic symbol's 22-hour stay en route to Beijing.

Instead of carrying the torch along a three kilometre (almost two mile) route from the white-marble Parliament in Pakistan's capital, as originally planned, the athletes will only run around the grounds of Jinnah Stadium.

Colonel Baseer Haider, an army official helping organise the event, said the route change was made because of the "overall security environment" and the risk of bad weather.

The flame travels to India on Thursday, home to nearly 100,000 Tibetan exiles including the Dalai Lama.

Thousands of police have been deployed there to avoid chaotic protests.

Meanwhile, the main venue for the Olympics has opened to the public in Beijing.

The city's National Stadium, nicknamed the Bird's Nest, will host sporting events as well as the opening and closing ceremonies.

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