Prime Minister Yoshihide Suga plans to hold phone talks with an executive of U.S. pharmaceutical giant Pfizer Inc. during his visit to Washington, the COVID-19 vaccine minister said Friday.

In their talks, Suga may seek additional supplies of coronavirus vaccines, though Taro Kono declined to provide details of their planned discussions during the prime minister's visit to the United States for talks with President Joe Biden.

Some Japanese government sources said Suga is arranging to hold talks with Pfizer CEO Albert Bourla via telephone on Friday or Saturday Japan time. The talks come as Japan's coronavirus inoculation campaign progresses very slowly compared with the United States and Europe.

Pfizer's COVID-19 vaccine is the only vaccine Japan has approved so far.

Japan started vaccinating older people against the novel coronavirus Monday, the second group to be inoculated following health care workers, before expanding to the rest of population.