AFP - Tokyo, which has lost a bid to host the 2016 Summer Olympics, offered on Friday to help Hiroshima and Nagasaki pursue their hopes of hosting the 2020 Games.

The two cities, which were devastated by US atomic bombs in World War II and later rebuilt into modern cities, announced on Sunday they were considering a joint Olympic bid as part of their campaign for a nuclear-free world.

"It is quite welcome that these two cities have stood up to go after the Olympics as a means of promoting peace," Tokyo governor Shintaro Ishihara told a news conference.

He said he had discussed the idea with Hiroshima mayor Tadatoshi Akiba, an advocate of nuclear disarmament who has called for the world to be free of atomic weapons by 2020.

"I told him that we will provide him with know-how as much as he may want," Ishihara said.

But the outspoken novelist-turned-politician did not rule out the possibility of Tokyo bidding for the 2020 Olympics itself.

"We must decide our position while I am in office," said Ishihara, whose third four-year term ends in 2011.

"What was difficult for Tokyo may not be easy for other cities. We must analyse such things before making a decision on Tokyo's position."

On October 2, Tokyo along with Chicago and Madrid failed in their bids to host the 2016 Summer Olympics, losing out to Rio de Janeiro.

Tokyo said it had spent 15 billion yen (165 million dollars) on the bid, which featured a plan to stage compact and "green" Olympics by reducing carbon emissions from Games-related projects and operations.

The International Olympic Committee is to announce the 2020 host city in 2013.

IOC vice president Thomas Bach said a joint Hiroshima-Nagasaki bid would have a "highly symbolic significance," according to Japan's Kyodo news agency.

"But it is not enough," Bach was quoted as saying in Paris on Thursday. "The bid cannot be successful with that only."

Japan has already hosted three Olympics -- the 1964 Summer Games in Tokyo as well as the 1972 and 1998 Winter Games in Sapporo and Nagano.

Rome, Venice and Palermo are reportedly preparing bids for the 2020 Summer Olympics. Other cities, including Cape Town, Durban, Dubai and Rabat, have also been mentioned as possible candidates.