TOKYO (Kyodo) -- Japanese Prime Minister Shigeru Ishiba has instructed Finance Minister Katsunobu Kato to closely monitor financial markets rocked by U.S. President Donald Trump's imposition of significantly higher tariffs.

Kato spoke to reporters after meeting with Ishiba at the prime minister's official residence, a rare Sunday gathering of Cabinet members that included Chief Cabinet Secretary Yoshimasa Hayashi and economic revitalization minister Ryosei Akazawa.

Ishiba's government is concerned about the fallout for Japan's export-oriented economy as well as the impact on foreign exchange and stock markets after U.S. reciprocal tariffs began to be levied late last week, fanning concerns about the outlook for global trade.

Kato said a possible telephone call between the U.S. and Japanese leaders was not discussed during the meeting. Ishiba has pledged to speak with Trump in the not-so-distant future to negotiate tariffs.

On Wednesday, Trump announced the introduction of reciprocal tariffs on U.S. trading partners to rectify what he views as imbalanced and unfair trade. An additional 25 percent tariff on cars produced outside the United States was also levied.

Tokyo shares have plunged, with the benchmark 225-issue Nikkei Stock Average down a record 3,339 points last week.