An investigation has been launched into allegations that thousands of sought-after tickets to the London Olympics have been sold by officials on the black market.

The International Olympic Committee has called an emergency board meeting after being presented evidence from the Sunday Times, suggesting the involvement of officials controlling tickets in 54 countries.

According to the paper, thousands of the best seats at the top events including the 100m final were up for sale after being drawn off from official supplies held by overseas national Olympic committees.

These committees are not allowed to sell their tickets abroad, or to resellers - but undercover reporters posing as Middle Eastern ticket touts found 27 agents and officials who were allegedly willing to do so.

The Sunday Times said one country's official ticket agency offered category AA tickets, the best seats in the stadiums, to the fake Middle Eastern tout for up to £6,000 each.

The allegations will be investigated by the IOC's ethics commission, a senior IOC source has confirmed.