TOKYO (AFP) - Tokyo's Olympic bid chief vowed on Tuesday to ensure safety if the city wins the 2020 Summer Games, as the sporting world reeled from twin blasts at the Boston Marathon.

"First of all, Tokyo is one of the safest cities in the world," said Mr Masato Mizuno, chief executive officer of the city's Olympic bid committee. "We'll do our best to prevent any of those wrongdoings."

He also played down the possibility of random bombings at the Olympics in which more than 200 countries take part.

Mr Mizuno, a former chairman of sporting goods giant Mizuno, said groups that conduct such acts of violence know it is "not very clever" to target the Olympics and become the "enemy of the whole world".

He said the bid committee needed to know what has actually happened in Boston before considering whether to review their security plan.

Mr Mizuno was speaking after a luncheon with the US and British chambers of commerce in Japan, both of which have expressed their support for Tokyo's 2020 Olympic bid against Madrid and Istanbul.

Tokyo, which hosted the 1964 Summer Games, lost its bid for the 2016 edition to Rio de Janeiro, the first South American city to host an Olympics.

Istanbul could become the first city with a predominantly Muslim population to host the Games.

Mr Mizuno told the luncheon: "We have much stronger city function."

"Now Rio's preparation is very, very late," he said. "More and more IOC (International Olympic Council) members want a safe pair of hands."

The 101 IOC members will vote to choose the 2020 host city on Sept 7 in Buenos Aires.