US President Barack Obama has delayed his visit to Japan next week by one day, a Japanese foreign ministry official said on Saturday, following a deadly shooting at a military base in Texas.

Japanese national broadcaster NHK and Jiji Press reported that Washington had asked Tokyo to reschedule the two-day visit to allow Obama to attend a memorial service for the 13 people killed in Thursday's shooting.

Obama had been due to arrive for his first trip to Japan on Thursday for talks with Prime Minister Yukio Hatoyama and to meet Emperor Akihito.

"The (US) government has requested a delay," a foreign ministry official told AFP, adding that the Japanese government had agreed to the request.

Obama would now be arriving on Friday and stay until today, the official said.

White House spokesman Robert Gibbs earlier told reporters in the United States that Obama would attend a memorial service for those killed when a Muslim army doctor went on the rampage at the Fort Hood base.

"When a service is scheduled the president will attend," he said, adding only that the timing of the memorial would be scheduled "for the convenience of the families".