Washington, Aug 27 (DPA): A group of Nobel Peace laureates have written a letter to US President Barack Obama asking him to deliver the keynote address at a November summit in Hiroshima.

The five Nobel winners, including former Soviet president Mikhail Gorbachev, said the Nov 12 Hiroshima summit would be a fitting venue for Obama to promote his agenda for a world free of nuclear weapons.

"There could not be a better venue for such a speech than Hiroshima - nor, perhaps, a more fitting forum than one presented by fellow Nobel Peace laureates," said the letter, posted on their website earlier this month.

Obama was awarded the Nobel Peace Prize in 2009, and is expected to be in Yokohama, Japan, for the November 13-14 Asia Pacific Economic Cooperation summit.

No sitting US president has ever visited Hiroshima. Hiroshima was the first site ever to be attacked with a nuclear weapon, when, Aug 6, 1945, a US plane dropped the bomb on the city to force Japan's surrender in World War II. More than 140,000 people died.

In addition to Gorbachev, the letter was signed by former South African president Federick W De Klerk, Poland's Lech Walesa, East Timor President Jose Ramos-Horta, and Oscar Arias Sanchez, the former president of Costa Rica.