A virus-tainted e-mail message criticizing Prime Minister Junichiro Koizumi's visits to Yasukuni Shrine has been sent to a number of people by an unidentified person pretending to be a Japanese diplomat, Foreign Ministry officials said Thursday.

The officials said the sender of the e-mail is using the name of a staffer at the Japanese Embassy in the United States and the ministry's official domain name: @mofa.go.jp

The e-mail comes with a document that is infected with a virus. The document says in Japanese that Koizumi's visits to Yasukuni sour "China-Japan ties," the officials said.

The ministry has warned the public not to open the attachment and to delete the e-mail if they receive it.

The ministry found on Tuesday that the e-mail had been distributed on the Internet.

Ministry officials said the embassy staffer whose name is used is not involved in the tainted message and that it was dispatched from a server not operated by ministry.

Koizumi on Monday paid homage at the Shinto shrine in Tokyo, angering China and South Korea and other nations that suffered from Japan's military aggression before and during the war.