TOKYO, July 8 (Reuters) - The United States is "saddened and shocked" by the shooting of Japan's former prime minister Shinzo Abe, US ambassador Rahm Emanuel said on Friday (Jul 8).

Japan's longest-serving prime minister, Abe, was taken to hospital bleeding after being shot while delivering a speech in the western city of Nara days before an upper house election, according to authorities and media.

"Abe-san has been an outstanding leader of Japan and unwavering ally of the US," Emanuel said in a statement.

"The US government and American people are praying for the well-being of Abe-san, his family, and the people of Japan."

Ahead of his meeting with Indonesia's Foreign Minister Retno Marsudi, US Secretary of State Antony Blinken said they are "deeply saddened and deeply concerned" by the news.

"We don't know his condition, we do know he's been shot and our thoughts and prayers are with him and his family, with the people of Japan," he added. "This is a very, very sad moment and we're waiting news from Japan."

Other leaders from around the world also expressed shock at Abe's shooting.

Australia's Prime Minister Anthony Albanese said in a tweet that "(their) thoughts are with his family and the people of Japan at this time".

Taiwanese President Tsai Ing-wen said she believes "everyone is as surprised and sad as (she is)" about the incident.

"On behalf of my government, I would like to severely condemn violent and illegal acts," she said.

"Former Prime Minister Abe is not only a good friend of mine, but also a staunch friend of Taiwan's. He has supported Taiwan for many years and spared no effort to promote the progress of Taiwan-Japan relations."

An Indonesian foreign ministry spokesman said in a statement, on behalf of the foreign minister, that she has "expressed her sympathies in the name of G20 foreign ministers to the Japanese foreign minister".

Japan's former Olympics minister Yoshitaka Sakurada, arriving at the Liberal Democratic Party (LDP) headquarters in Tokyo, said: "I can't believe that something like this could happen in the 21st century.

"There's still Russia, that was beyond expectations as well, but I can't believe something like this could happen in Japan."