Japan's embattled prime minister will not visit the United States next month at the invitation of U.S. President Barack Obama.

Japan's top government spokesman told reporters of the decision Friday, saying such a visit was impossible given Japan's political situation. Spokesman Yukio Edano also said Tokyo had already informed the U.S. ambassador to Japan , who showed understanding.

The announcement comes just days before U.S. Vice President Joe Biden is scheduled to visit Japan as part of an tour that includes China and Mongolia.

Japanese Prime Minister Naoto Kan has come under intense criticism for the country's uneven response to the March 11 earthquake and tsunami that devastated parts of the northeastern coast. The dual disaster left at least 20,000 people dead or missing. Another 100,000 were forced to leave their homes following meltdowns at the Fukushima Daichi nuclear plant.

Mr. Kan has previously said he would step down after a series of key bills are approved by parliament. That could happen as soon as next week.

Mr. Kan's successor will be Japan's sixth prime minister in five years.